Improving farm animal welfare
Master Thesis
Alexandra Antonides, 3032213
Master Programme: Neuroscience & Cognition
Track: Behavioural Neuroscience
Supervisor: Dr. Saskia S. Arndt
Animals in Science & Society, Faculty of Veterinary Medicine, Utrecht University
And I am my brother’s keeper
And I will fight his fight
And speak the word for beast and bird
Till the world shall set things right
– Ella Wheeler Wilcox
2
3
Abstract
The globally growing demand for animal products has put a strain on producers in order
to keep producing profitable. However, the public’s concern about the welfare of farm
animals has recently been increasing. Defining the concept ‘welfare’ has proven to be
difficult, as it is subject to personal and cultural ethics and values. In this thesis, an
overview of welfare definitions and scientific findings on negative and positive welfare
indicators is given. Although negative welfare indicators have been studied extensively,
the study of positive welfare indicators is relatively new in welfare science. Combining
these findings, together with encouraging natural behaviours, can help to improve the
welfare of farm animals. Furthermore, factors are discussed that influence farm animal
welfare, such as conflicting interests, housing systems and farmer attitude. Concluding,
a short overview of current farming practices in cattle, pigs and poultry is given. An
interesting finding is that improved welfare is often accompanied by improved health
and production, which is beneficial for multiple stakeholders. Much has been achieved in
terms of improving farm animal welfare since animal welfare concerns have been
arising. In order for these developments to continue, all stakeholders (the government,
the consumer and producers) must respect each other’s needs and interests. It should be
realized that animals are stakeholders in this industry as well, and that they depend on
humans to take the matter of their welfare seriously. With combined effort, willingness
and respect, it is possible to make the future of farming sustainable for all parties
involved.
Acknowledgements
Writing a thesis demands a lot of self-discipline and social isolation, which is difficult to
accomplish during summer months. Luckily, many people around me have been very
supportive and motivating, helping me to stay focused and work hard. For that hardneeded support, I would like to thank Björn, Iris, Judith, Tessa and my parents. Thanks to
dr. Saskia Arndt for her willingness to be my supervisor for this thesis, her critical views
and for always being available for questions. I have learned a lot about farm animals and
farming practices in a short amount of time, and have been glad to learn that the welfare
of farm animals is receiving growing attention by all stakeholders in this business, as
well as in the scientific field. There are some very promising current and future
developments which give the proper treatment of farm animals the attention that – in
my opinion – it deserves. Spending time with any animal, be it a cat, rabbit, cow or pig,
makes one appreciate their species-specific behaviours and needs. The fact that farm
animals are kept for our growing demand for meat and other food products should not
make a difference as to how we respect and treat those needs. I believe that we should
allow each animal to be able to live a life worth living, with at least some aspects of
pleasure, comfort and enrichment. Luckily, I am not the only one with this view, and I
hope and do believe that people that share this view with me can and will make a
difference in improving the quality of life for farm animals.
4
5
Index
1 Introduction ............................................................................................................................ 8
2 Assessing welfare .............................................................................................................. 11
2.1 Definitions of Welfare ..................................................................................................................... 11
2.2 Negative welfare indicators.......................................................................................................... 12
2.2.1 Hunger and thirst ...................................................................................................................................... 13
2.2.2 Injury and disease ..................................................................................................................................... 14
2.2.3 Pain .................................................................................................................................................................. 14
2.2.4 Stress and fear ............................................................................................................................................ 15
2.2.5 In sum ............................................................................................................................................................. 16
2.3 Positive welfare indicators ........................................................................................................... 16
2.3.1 Motivation and affect ............................................................................................................................... 17
2.3.2 Play behaviour ............................................................................................................................................ 18
2.3.3 Allogrooming ............................................................................................................................................... 19
2.3.4 Vocalizations ............................................................................................................................................... 19
2.3.5 Physiological indicators of positive affect ....................................................................................... 20
2.3.6 In sum ............................................................................................................................................................. 21
2.4 Natural behaviour ............................................................................................................................ 21
3 Farm animal welfare ........................................................................................................ 24
3.1 Factors that influence farm animal welfare ........................................................................... 24
3.1.1 Conflicting interests ................................................................................................................................. 24
3.1.2 Ethical concerns ......................................................................................................................................... 26
3.1.3 Housing systems ........................................................................................................................................ 27
3.1.4 Farmer’s handling and attitude ........................................................................................................... 28
3.1.5 Transport and slaughter practices ..................................................................................................... 29
3.1.6 Summary ....................................................................................................................................................... 30
3.2 Cattle...................................................................................................................................................... 30
3.2.1 Dairy cows .................................................................................................................................................... 30
3.2.2 Calves.............................................................................................................................................................. 33
3.3 Pigs ......................................................................................................................................................... 35
3.3.1 Sows ................................................................................................................................................................ 35
3.3.2 Growing-finishing pigs ............................................................................................................................ 37
3.4 Poultry .................................................................................................................................................. 39
3.4.1 Laying hens .................................................................................................................................................. 40
3.4.2 Broiler chickens ......................................................................................................................................... 42
4 Discussion ............................................................................................................................. 45
4.1 Addressing farm animal welfare ................................................................................................ 45
4.2 Influence of scientific research ................................................................................................... 45
4.3 Complexity of the issue of farm animal welfare ................................................................... 47
4.4 Concluding remarks ........................................................................................................................ 48
5 References ............................................................................................................................ 51
5.1 Sources of images used .................................................................................................................. 60
6
7
1 Introduction
The domestication of animals by humans goes back thousands of years. Animals have
been domesticated in human history for providing resources such as pelt and meat, but
also for protection, aid in hunting, and transport (Ucko & Dimbleby 1969). One of the
largest influences on man’s way of living has been the domestication of farm animals.
During a process called Neolithisation, human societies changed their way of life from
hunting-gathering to food production based on farming of domesticated animals (Vigne
2011). This allowed them to create settlements as they were no longer forced to live a
nomad life, and thus had a major impact on human demography. Furthermore, the
emergence of farming made humans less dependent on seasonality of resources. In the
course of human history farming intensified enormously, to such an extent that livestock
populations worldwide now exceed hundreds of millions (FAO 2009). As it is estimated
that the human population will exceed 9 billion in 2050 (UN Population Division 2011),
the demand for animal products will keep increasing over the coming decades. In fact,
the UN Food and Agriculture Organization expects that in 2050 compared to 2010, 2.3
times as much poultry meat and between 1.4 and 1.8 times as much of other animal
products will be consumed (FAO 2006).
With such huge demands, there is a considerable burden on farmers in meeting
these demands, and efficient production methods are sought in order to keep
production profitable. Over the past few decades however, there is raised ethical
concern about the well-being of farm animals in extensive livestock production. Images
of chickens packed together with millions in a confined space, sows in farrowing crates
unable to build nests or even move properly, calves isolated from their mothers directly
after birth; these are all examples of practices which are repugnant to the general public.
Proper treatment of animals has become more important to society (especially the
Western culture, e.g. Eurobarometer 2007), and the idea that animals are sentient
beings that deserve a good quality of life is becoming more and more widespread.
Improved understanding of animal functioning, cognition and behaviour has amplified
the interest in animal welfare over the past 30 years (Broom 2011).
The first step in improving animal welfare was made by the Brambell committee,
set up in 1965 by the British government. The resulting Brambell Report contained the
familiar “Five Freedoms”, which state that animals should be (1) Free of hunger and
thirst; (2) Free from discomfort; (3) Free from disease, injury or pain; (4) Free from fear
8
and distress, and (5) should have the freedom to express normal behaviour (Brambell
1965). Although this was a very important step in improving animal welfare, it has been
criticized that freedoms 1 to 4 focus only on the absence of negative feelings or
experiences. It is now widely accepted that animals can suffer, based on the results of
extensive research on pain and suffering in animals, and a lot has been done to reduce
this suffering. Indeed, this has improved the welfare of animals to a fair extent. However,
the well-being or welfare of an animal cannot accurately be assessed merely by the
absence of negative experiences. An animal that is free of pain, suffering and hunger is
not necessarily a ‘happy’ animal. To quote the Farm Animal Welfare Council (2011), the
question is not just if animals suffer or whether their needs are met, but rather if they
have a life worth living. In other words, as Yeates and Main (2008) reason: ‘What use is
there in satisfying an animal’s vital needs, if the life the animal then lives is devoid of any
enjoyment?’ The presence of positive emotions may even be a predominant part of wellbeing, as argued by Boissy et al. (2007). Thus, scientists are starting to realize that good
welfare should also include the assessment of positive affects, in order to be able to say
anything sensible about the well-being of animals. This is resulting in a shift of focus in
animal welfare research from negative to positive welfare assessment (Boissy et al.
2007; Yeates & Main 2008).
Assessing positive aspects of welfare is not easy. As Fraser and Broom pointed
out in 1990: ‘Our ability to make direct measurements which identify pleasure is
extremely limited,’ although: ‘Research on the practicality of direct behavioural and
physiological indicators of pleasure is much needed’ (Fraser & Broom 1990, p276).
Even now, some 20 years later, positive welfare research is still in its infancy. The
difficulty in assessing positive welfare in animals lies in the very nature of it: feeling
good and being happy are very subjective and personal matters, which are difficult to
capture scientifically. The World Health Organization’s definition of ‘health’ in humans
illustrates this problem: they define health as ‘a state of complete physical, mental and
social well-being’ (WHO, 1946). Not only does ‘complete well-being’ sound rather
impossible to achieve, this definition also poses a problem in assessing health. How can
one determine how mentally or socially healthy a person is at a given point in time, let
alone in general? Similarly, how can we assess how satisfied an animal is with the life it
is living? Negative emotions such as suffering and fear are easier to quantify and
measure than positive emotions, or even more tenuous concepts such as ‘a good quality
9
of life’. Negative events have a more pronounced effect on physical output of animals,
such as freezing behaviour, an increased heart rate and high levels of stress hormones in
the blood. Long-term effects of bad welfare are also well-known, for example anhedonia,
pathological anxiety and stereotypies (Fraser & Broom 2007). It should, however, be
noted that at least some forms of stereotypies are believed to be a coping mechanism for
animals to reduce stress and frustration (Mason 1991). For example, tethered sows
showing high occurrence of stereotypies had a reduced heart rate during bouts of
stereotypies, indicating that this behaviour reduces stress and thus helps the animal to
cope with the situation (Schouten & Wiegant 1997). Positive experiences have a more
subtle effect on physiology and behaviour, making it more difficult to measure. This, at
least partly, explains why scientists have been focusing on negative aspects of welfare in
the past and positive affects have been often neglected. Now that there is a pressing
demand for positive welfare assessment, research is beginning to focus on how to assess
positive emotions and affects in animals, with some very promising first results and
indications.
In this thesis, I will give an overview of past and current developments in animal
welfare research, and resulting implications for farming practices. As indicators of
impaired welfare have been studied and elucidated to a fair extent, the focus of this
thesis will be improvement of animal welfare. After reviewing definitions and measures
of animal welfare, I will focus on farm animals, discussing factors that influence farm
animal welfare. Thereafter, I give a short overview of current farming practices of three
animal species in husbandry practices that are most intensively farmed: cattle, pigs and
poultry. In the concluding part of this thesis, I will discuss past and current
developments and future prospects of farm animal welfare.
10
2 Assessing welfare
2.1 Definitions of Welfare
When talking about a concept such as welfare, it is first and foremost important to
define the matter that is being discussed. Unfortunately, many definitions have been
proposed, and consensus about what welfare exactly is has not been reached yet.
Defining the term welfare is complicated, as discussions about animal welfare are the
result of ethical concerns. These concerns, for example about how animals should be
treated by humans, differ between cultures, time and individuals, which makes the
definition of welfare rather a more subjective than a scientifically definable concept
(Tannenbaum 1991; Stafleu et al. 1996). For example, the Brambell committee (1965)
defines animal welfare as ‘a wide term that embraces both the physical and mental wellbeing of the animal.’ Although this will sound acceptable for most people as a definition
of what they believe animal welfare entails, scientifically this definition is not very
usable. The scientific approach of a concept demands clear definitions with measurable
parameters, in order to objectively assess it. However, as Stafleu et al. (1996) remark, it
is also important to remember that animal welfare should not solely be about measuring
parameters, risking the loss of the moral concept of animal welfare. The interplay of two
distinct fields as ethics and science makes it difficult to create a definition that scientists
are satisfied to work with. The inherent ethical component and thus the subjective and
emotional charge that the term ‘welfare’ carries, has long kept scientists from trying to
scientifically approach this subject.
Over time, more specific definitions of animal welfare have emerged, such as the
definition by Broom (1986): ‘The welfare of an individual is its state as regards it
attempts to cope with its environment.’ Tannenbaum (1991) defines welfare similarly:
‘Welfare refers to a state that includes some measure of a successful life.’ More
specifically, Webster (2005) further defines this success of coping, defining welfare as
being able to avoid negative and pursue positive events: ‘The welfare of a sentient
animal is determined by its capacity to avoid suffering and sustain fitness.’ Thus, he
abbreviates: good welfare means being fit and feeling good. These definitions all
incorporate the long-term aspect of welfare, as they suggest an extended period of time
through which welfare is formed and experienced. Moreover, they imply that being able
to predict and control interactions with the environment are crucial to the welfare of the
11
animal. An important recent development in defining welfare is that the definition is
being adjusted to include the experience of the animal: Dawkins (1990) states that
‘animal welfare involves the subjective feelings of animals’. Bracke et al. (1999) define
welfare as ‘the quality of life as perceived by the animal itself.’ Although such definitions
are again scientifically difficult to employ practically, it does indicate that it is believed
that welfare is mainly about the perception of the animal, and not about human interests
and values. More specifically, Duncan (1993) claims that ‘welfare is about both positive
and negative emotions and, therefore, about the satisfaction of needs and desires.’ The
faculty of veterinary science in The Netherlands states that ‘an individual is in positive
welfare when it has the freedom to react adequately to pain, discomfort, hunger, stress
and to conduct normal behavioural patterns that allow him to adapt to the demands of
the environment and enable it to reach a state which is experienced as positive’ (Ohl &
van der Staay 2011). This definition incorporates both the coping ability and the
subjective emotional state of the animal.
It may be clear that reducing negative emotions and increasing positive
experiences are both important in improving animal welfare. Once we know what an
animal experiences as negative and positive, and under what circumstances it is most
satisfied, practices can be adjusted in order to improve animal welfare. Broom (1986)
suggests that difficulty in coping is ‘recognizable’ by scientific study, as it may be
associated with pain and suffering in the individual. Although we know little of the
feelings of animals, he claims, we may measure behavioural and physiological responses
that are the result of poor welfare. It is now believed that we can use responses in
behaviour and physiology to assess positive indicators of welfare just the same (Boissy
et al. 2007; Yeates & Main 2008). In this chapter, I will discuss indicators of negative and
positive welfare and the importance of natural behaviour for the welfare of animals.
2.2 Negative welfare indicators
The initial focus of animal welfare concern has been on negative experiences or
emotions, such as hunger, pain, fear and stress, which are widely accepted indicators of
reduced welfare. It is important to note here that negative emotions in animals are in
fact adaptive, and necessary for animal survival. The sensations of pain and fear are
evolved reactions in order to avoid injury and danger (Bateson 1991), which help the
animal to cope with and survive environmental challenges. A fearless animal will not
avoid predators, which may be fatal. An animal that does not feel pain will easily get
12
injured and will not recover from injury as soon as an animal that does feel pain.
Therefore, it should not be pursued to completely diminish negative emotions, as they
are an important part of the natural behavioural repertoire of the animal, and help the
animal to cope and respond appropriately (also see section 2.4). The important issue is
that the adaptive ability of the animal should not be exceeded by negative experiences in
the long run, i.e. leaving the animal unable to cope with challenges, which can be
prevented by compensating negative with positive experiences (Ohl & Hellebrekers
2009).
2.2.1 Hunger and thirst
Feelings of hunger and thirst can easily be overcome by providing enough food and
water to the animal. Food requirements for farm animals are now well-known (e.g.
Bondi 1987) and have been studied extensively, as animal food intake and energy
expenditure are important factors for the efficiency of production systems. However,
some problems with feelings of hunger may arise when animals are given their daily
required intake in one or two portions per day which are depleted easily. For example,
offering isolated calves milk in a bucket results in fast depletion of the milk, and causes
behavioural problems such as redirected sucking behaviour (section 3.2.2; Hammell et
al. 1988). In most farm animals, much of the behavioural repertoire includes searching
for food and spending a large amount of time foraging, such as rooting in pigs (Studnitz
et al. 2007), grazing in cows (Albright 1993), and scratching and pecking in chickens
(Shields et al. 2005). Therefore, it may be that animals that are given their required
amount of food in few large portions may result in abnormal behaviour in between these
feeding bouts, which may be due to, or at least accompanied by, strong feelings of
hunger. It may be advised and stressed that when feeding animals, one must also
consider the natural foraging behavioural needs of the animal. Some sense of hunger is
obviously natural and should not raise much concern. Moreover, an animal that is fed
once or twice daily does not necessarily have an impaired welfare, as its biological
functioning such as growth rate is not impaired. However, it is important that negative
emotions, e.g. feelings of hunger, are compensated by positive experiences, such as
environmental enrichment and at least receiving food regularly.
13
2.2.2 Injury and disease
Another important part of recognizing and reducing bad welfare is the occurrence of
injury and disease. The use of antibiotics, vaccinations and regular medical treatment of
disease and injuries have become standard in farming practices, and has resulted in
improved monitoring and prevention of diseases and injury (e.g. PostNote 2011). There
is a recently emerged concern about the dangers of large-scale non-therapeutic use of
antibiotics in livestock production for both animal and human health, as bacterial
resistance to antibiotics is increasing (Gilchrist et al. 2007). This may result in infections
and diseases that can no longer be treated with antibiotics, which may in its turn result
in epidemic diseases. A recent example is the emergence of the antibiotic resistant
hospital bacterium MRSA (Chen et al. 2012).
Housing systems have been adjusted over time in order to prevent common
injuries and infections, as well as the transfer of diseases. For example, stall size, stall
hygiene and the type of bedding have been shown to influence the occurrence of mastitis
in cows (Elbers et al. 1998; Hogan & Smith 2003). Injuries caused by redirected
behaviour such as sucking and biting by conspecifics has led to practices as tail docking
in pigs to prevent tail biting, and beak trimming in chickens to avoid feather pecking and
cannibalism. This is, however, clearly only a means of avoiding harm being done, instead
of adjusting conditions so that the abnormal redirected behaviour is no longer
performed, which is the actual welfare issue that should be considered.
2.2.3 Pain
The function of pain is believed to be minimizing and avoiding damage to one’s body and
speeding recovery once damage has been done, through protective behaviour of the
painful site (Bateson 1991). Animals show numerous physiological, (neuro-)anatomical
and behavioural similarities with humans that suggest similar subjective experiences of
pain. These include identical pain fibers, nervous pathways connecting pain receptors to
higher brain structures, and similar behavioural and physiological responses to pain
(Bateson 1991). Behavioural responses to pain are suppression of normal behaviour
(e.g. grooming and eating), postural changes, defense and avoidance behaviour, and
attention directed towards the site of their pain (licking and scratching). Anatomical
indicators include locomotor problems due to lesions or injuries. Long-term pain which
an animal is unable to successfully avoid can result in learned helplessness (Zimmerman
1986), where the animal shows apathic and unresponsive behaviour.
14
Physiological responses to pain are raised blood pressure, raised stress hormone
levels in the blood, increased respiratory rates, increased heart rate, dilated pupils and
increased vocalizations (Rutherford 2002). These responses are in general stressresponses, which make it difficult to use them specifically as pain indicators. The fact
that anesthetics reduce or remove feelings of pain in humans and pain-related
behaviours in both humans and other animals, strongly indicates that pain is indeed
subjectively experienced in animals expressing such behaviours. The difficulty in
assessing pain is that some animals – in particular prey animals – have evolved ways of
masking pain responses (Sanford et al. 1986), for example to prevent suspicion by
predators. This is why in particular behavioural pain responses cannot and should not
be generalized for all species. Another example is that in social species, the expression of
pain may be informative for conspecifics (Fraser & Broom 1990), which would increase
the expression of pain-related behaviours compared to non-social species. Hence,
factors such as the social structure, biology and evolution of a species are important to
include in pain assessment.
2.2.4 Stress and fear
Stress and fear are states of the body that emerge when immediate action is required in
order to respond appropriately to a challenge, such as a (possible) threat by a predator
or conspecific. These responses are natural and adaptive, as they help the animal to
avoid possibly harmful events. This bodily reaction is also called the ‘fight-or-flight’
response, and includes activation of the sympathetic nervous system and secretion of
adrenaline into the blood stream. Responses are similar to the previously discussed
indicators of pain (which induces stress, making it difficult to use these responses to
assess either one apart from the other), such as suppression of activities as feeding and
grooming, flight or defense responses, increased heart rate, dilated pupils and increased
respiration rates (Broom 1988). A physiological indicator of immediate stress is raised
blood concentrations of stress hormones, such as cortisol. Cortisol is, however, not a
clear indicator of a stress response to negative events, as it is also released in exercise,
mating and nursing (Borg et al. 1991). Predictability and controllability are important
factors in stress, as these influence the stress response more than the actual stressor
itself (Weiss 1972). Therefore, stress is not only a physiological reaction, but also an
emotional one.
15
The exposure to intense or prolonged stressors lead to reduced immune
functioning, causing increased occurrence of disease, reduced reproduction rates and
abnormal behaviours (Moberg 1985). One important long-term stressor is the inability
to cope with environmental challenges. Coping is being able to meet needs that the
animal has (Broom 1988). When coping succeeds, the animal can adapt to the
environmental conditions – when coping fails, the animal becomes stressed, reducing its
fitness and welfare. Behavioural indicators of long-term stress include inactivity,
unresponsiveness, redirected behaviours and stereotypies (Fraser & Broom 2007). As
mentioned before, such behaviours may be a means for the animal to cope with the
situation, reducing stress and feelings of frustration, and may thus help the animal to
feel better under the circumstances it is in.
2.2.5 In sum
Indicators of bad welfare may be anatomical, physiological or behavioural. When
looking at physiology, short-lived stressful events suppress behaviour such as grooming
and feeding, and increase heart rate, respiration rates and raised blood levels of stress
hormones. Long-term physiological effects of impaired welfare include reduced
functioning of the immune system and thus high occurrence of disease and infections.
Behavioural measures of short-term stressors are freezing behaviour, vocalizations,
avoidance, locomotor problems and flight reactions. Long-term behavioural indications
of reduced welfare are inactivity, unresponsiveness, stereotypical behaviour and
abnormal redirected behaviours. However, the expression of such behaviours may be a
mechanism helping the animal to cope with aversive situations.
2.3 Positive welfare indicators
Positive emotions and affect are thought to have evolved in order to stimulate behaviour
that is beneficial for the animal on a short and/or long term, such as obtaining resources
(Fraser & Duncan 1998). Sensory pleasures are often linked to returning the body to
homeostasis, such as eating when hungry, heating when cold, and relaxing when
aroused; making the extent of pleasure depend on the previous deviation from
homeostasis (Cabanac 1971). This is a sensation we also experience ourselves: when
very hungry for example, any food will taste good. Behavioural pleasures that have longterm benefits such as sexual behaviour resulting in reproduction, and (allo)grooming
resulting in personal and mutual hygiene, are thought to be rewarding in itself. As the
16
behaviour and the benefits are separated in time, these behaviours are believed to be
motivating for the animal because they are satisfying to perform, rather than because of
the benefits in the long run (Friend 1989). The functional explanation as to why these
behaviours evolved are then the long-term benefits such as good hygiene and successful
reproduction, whereas the causal explanation of the behaviour is because they are
pleasant to perform for the animal.
The recent shift of focus from negative to positive welfare has been mainly due to
the increasing awareness that assessing and reducing negative welfare alone is
incomplete. Positive emotions and affects are increasingly included in welfare
assessment, in order to fully determine an animal’s state of welfare. It has been
proposed that there is a bipolar welfare continuum stretching from negative to positive
welfare (Feldman Barrett & Russell 1998). In this view, positive welfare assessment is
an expansion of existing welfare science, investigating the other end of this continuum.
Although investigating positive emotions and affects is fairly new in welfare research,
the number of studies and theories on indicators of positive welfare is increasing. Here, I
will give an overview of recent findings and current ideas of positive welfare indicators.
2.3.1 Motivation and affect
Motivation is the drive to access or avoid a resource, and is associated with ‘wanting’.
When obtaining a resource that an animal wants, the resulting positive affect can be
described as ‘liking’, as opposed to negative affects such as distaste or aversion (Yeates
& Main 2008). When assessing positive welfare, it is important to be able to determine
what an animal wants and what it likes, to which end behaviour is an important read-out
parameter. Preference tests, especially those that include ‘costs’ for resources that can
be obtained, can give an indication of what is important for an animal. For example, in a
preference study with mink, doors giving access to different kinds of resources were
weighted, making it possible to determine how much effort the animal would make in
order to reach the resource (Cooper & Mason 2000). The outcome showed that
increasing door weights (up to 1 kg) did not reduce the time they spent swimming in a
compartment with water, manipulating novel objects and occupy a hay box, indicating
that those resources are important to them. Using this ‘consumer demand’ approach, it
can be investigated how much effort an animal is willing to invest in order to get access
to a resource (Cooper & Mason 2001), i.e. what kind of value or ‘price’ a resource has for
17
the animal. Simpler preference tests can show what resources an animal prefers over
others. Such a preference test in chickens showed that they preferred food particles as
flooring material for foraging behaviours over wood shavings, pelleted wood fiber and
Astroturf mat, whereas time and number of dustbaths was highest on pelleted wood
fiber (Scholtz et al. 2010). Such study designs can be used in order to determine what an
animal is motivated towards and what it prefers, making it possible to include these
preferences in the design of housing systems and policy making. In preference studies, it
is important to realize that preferences and behavioural needs may differ during the day
or along the reproductive cycle (e.g. Weeks & Nicol 2006), as well as by age and gender.
As physiological markers of positive affect are not yet fully elucidated,
behavioural markers are currently used in general. Behaviours that are expressed when
animals are in positive affective states may differ greatly between species. In domestic
pet animals, behaviours that are well-known to be expressed during positive affect are
for example purring in cats and tail-wagging in dogs. Furthermore, different postures
and facial expressions in dogs and cats are known to signal anger, fear or pleasure
(Bradshaw & Nott 1995; Overall et al. 2005). If similar expressions of behaviour that
indicate pleasure or happiness can be found in other animals, they can be used in
determining positive affect. Thus, it is important to study animals at times when they are
believed to be content and feel pleasure or enjoyment, in order to use the expressed
behaviour as markers for positive affective states.
2.3.2 Play behaviour
Although the exact function of play remains a mystery, it is thought to be an indicator of
good welfare. Play is not or less performed under poor conditions (after castration in
lambs, Thornton & Waterman-Pearson 2002; in cold weather in piglets, Newberry et al.
1988) and play duration and intensity increases after periods of play deprivation
(Jensen 1998). It is believed that play indicates that the immediate needs of the animal
are met, which makes it a useful indicator for positive welfare. Play behaviours can be
measured and used as an indication of welfare (Blackshaw et al. 1997), and often include
short and abrupt movements. Theories about the function of play include preparing the
animal for challenges later in life (Spinka et al. 2001); self-assessment of social and
physical abilities (Thompson 1998); and training of the muscles (Byers & Walker 1995).
18
The number of studies focusing on farm animal play behaviours is increasing,
making this information available for use in welfare assessment. For example, play
behaviour in calves is now known to consist mainly of locomotor play, including
running, bucking and kicking (Jensen & Kyhn 2000). In piglets, play behaviours include
head tossing, pawing, hopping, pivoting and flopping (e.g. Dudink et al. 2006).
2.3.3 Allogrooming
Allogrooming is affiliative behaviour in which animals groom each other by gently
biting, nibbling, or licking each other. Allogrooming is seen in most farm animal species,
and is believed to increase bodily hygiene, to help form and maintain social bonds and to
reduce tension in groups (Sato et al. 1991). Grooming in cattle (Sato & Tarumizu 1993)
and grooming simulation in pigs (Hansen & von Borell 1999) have been shown to reduce
heart rate, which shows that it has a relaxing effect. The combination of findings that
close relationships are formed between individuals (Reinhardt & Reinhardt 1981; Sato
et al. 1993) and the fact that mixing with unfamiliar conspecifics results in aggression
(Pitts et al. 2000), indicates that affiliative behaviour positively influences an animal’s
state of welfare. However, as excessive allogrooming may cause harm, irritation and
aggression in the receiver, and frequencies of allosocial behaviours are increased in nonenriched environments (Beattie et al. 1996), it should be further investigated what
aspects and which amount of allogrooming actually signals positive welfare. There are
some indications that high occurrence of self-grooming indicates poor welfare, as it is
decreased in group-housing and increased in barren or restricted environments (Kerr &
Wood-Gush 1987). Therefore, the occurrence of self-grooming in combination with
observations of allogrooming may help in determining the welfare of the animal.
2.3.4 Vocalizations
Vocal signals of animals are easy to record and therefore measurable and quantifiable.
This makes the number and type of vocalizations useful indicators for welfare, if they
can signal positive or negative affective states. Although negative events accompanied
by pain or stress are known to elicit specific vocalizations in farm animals (Manteuffel et
al. 2004), positive vocalizations of farm animals are still scarcely studied. Studies in
other animals show promising results, indicating that vocalizations may indeed be
useful to assess positive welfare. In rats, high-frequency ‘chirping’ occurs in social play,
anticipation of reward and human tickling (Knutson et al. 2002), providing evidence that
19
this vocalization signals positive affect comparable to human laughter. In cats, purring is
believed to indicate a pleasurable feeling, as it is expressed in positive social interactions
such as petting and nursing, during rubbing against other animals or objects, and in
anticipation of rewards (Moelk 1944; Crowell-Davis et al. 2004).
In cattle, vocalizations have been shown to signal age, reproductive state, fitness
and social status (Watts & Stookey 2000). The acoustic structure of alarming barks of
pigs differs from playful barks, indicating that these different barks reflect affective
states in pigs (Chan 2011). In sheep, low pitched bleating is expressed by rams when
approached by a ewe in estrus, and by ewes nursing their young (Fisher & Matthews
2001). Such vocalizations possibly signaling positive affect in farm animals may be used
in welfare assessment. As recording and analyzing vocalizations is easy and noninvasive, this is a promising developing field of positive welfare research.
2.3.5 Physiological indicators of positive affect
Research conducted on neurological and physiological markers of positive affect
provide evidence that these behaviours indeed make the animal feel better and improve
welfare. Although physiological markers to assess positive affect are underexposed,
some promising fields for the assessment of positive affect may be heart rate variability,
immune system functioning, and the measurement of neurotransmitters linked to
positive affect in humans (Yeates & Main 2008). One clear indicator that positive
affective states increase welfare comes from studies in humans, showing a correlation
between positive affective states and physical health (Pressman & Cohen 2005).
Neurotransmitters and similarly acting drugs which are known to elicit positive
affective states in humans, such as opioids and dopamine (Burgdorf & Panksepp 2006),
induce social interaction and play behaviours in animals when administered
(Vanderschuren et al. 1997; van Ree et al. 2000) and are linked to positive behaviours in
animals, such as social bonding and reward behaviour (Boissy et al. 2007). Furthermore,
the inability to perform behaviours that are thought to induce positive emotions in an
animal results in withdrawal signs similar to drug addiction withdrawal (van Ree et al.
2000). Therefore, it can be assumed that such behaviours – social behaviour, grooming,
play – indeed make animals feel good and are very rewarding for the animal, and that
the inability to perform these behaviours cause problems to an animal’s welfare.
20
2.3.6 In sum
Evidence from studies on behavioural and physiological markers of positive affect show
that social behaviour, play behaviour and allogrooming are reliable indicators of positive
affect and are, therefore, linked to positive welfare. Specific play behaviours may differ
between species, just as vocalizations and other expressions of positive affect. This
makes it important to study a certain animal species’ behaviour in situations in which it
is believed to be content, in order to determine which behaviours signal positive
emotions. Neurotransmitters, such as opioids and dopamine, are linked to and induce
positive behaviours such as social behaviour, play and grooming, providing evidence
that these behaviours indeed are expressions of positive affect. Deprivation of such
behaviours causes withdrawal symptoms comparable to drug addiction withdrawal,
showing that not being able to perform these behaviour results in impaired welfare.
2.4 Natural behaviour
As mentioned before, both negative and positive emotions are important for animals.
Negative emotions make animals avoid danger and harm, whereas positive emotions
make animals obtain resources and attain states that are beneficial and pleasurable.
Both can help the animal to cope with environmental challenges in order to survive and
reproduce successfully. Negative emotions are, therefore, not bad for the animal per se,
but aid the animal in responding to its environment just as much as positive experiences
and emotions do. Coping with environmental challenges, therefore, comprises
behavioural and physical adaptations to both positive and negative events (Ohl & van
der Staay 2011).
In natural circumstances, the animal is thus, in general, capable to successfully
react to challenges of its environment, especially as it is that environment that it is
evolutionary adapted to. However, the challenges faced by farm animals are very
different from those of the environment they evolved in, possibly resulting in frustration
and other unpleasant feelings (Fraser & Weary 2003). In turn, these frustrations can
result in harmful behaviour for the animal itself or for conspecifics. Such harmful
behaviours and frustrations may also make animals difficult to handle for caretakers.
Moreover, it may influence the caretaker’s behaviour and attitude towards the animal
negatively, which can have pronounced effects on animal fear levels and productivity
(section 3.1.4). An example of a challenge an animal is not adapted to is physical
21
constraint, which prevents the animal from expressing natural behaviours such as
foraging and nest-building. Although a constrained animal may be able to feed and to
farrow, the needs for those behaviours remain, resulting in frustration and abnormal
behaviour (Fraser & Broom 2007). It is this need to express natural behaviours which is
often not considered in the stall designs of husbandry practices, as it often makes little
difference for productivity outcomes. The inability to perform natural behaviours is
however one of the main concerns of society for farm animals and is often what makes
people feel uncomfortable about farming practices. For example, hens in battery cages
do receive enough food and water and will lay eggs, hence the main biological functions
of the animal are not hampered. The concern for hens kept in this way is that they have
no freedom to move around, explore, and express natural behaviours which they feel the
need to perform. The Brambell report (1965) captured this concern in their fifth
freedom, in which they state that the animal should have the freedom to display normal,
species-specific behaviour.
A part of natural behaviour is being able to respond and react to the environment,
i.e. maintain a dynamic interaction with the environment (Ohl & van der Staay 2011). It
is suggested that the ability to adapt to environmental challenges can be used as a
measure for animal welfare (Korte et al. 2007) and that the inability to adapt results in
poor welfare (Salomons et al. 2009). Thus, the emotional state of an animal can be
deducted by the interaction with its environment (Ohl & Hellebrekers 2009). Barnard
and Hurst (1996) state that ‘welfare can be interpreted only in terms of what natural
selection has designed an organism to do and how circumstances impinge on its
functional design.’ Being unable to adapt to the environmental circumstances can
prevent the animal from reaching a state which it perceives as positive (Ohl & van der
Staay 2011). Thus, in order to improve animal welfare, natural behaviour and therefore
behavioural needs should be considered, and it should be assessed whether the animal
is able to adapt to and cope with challenges it faces in its environment.
Adjustments to the daily life of animals and handling practices which stimulate
the animal in a positive way, may increase animal welfare. Anticipation of receiving
wanted resources such as food or space may induce pleasant anticipatory feelings and
behaviours in the animal (Dudink et al. 2006). Positive contrast, where the animal
receives more of something wanted than it expects, may also help in inducing positive
emotions in animals (Crespi 1942). In order to avoid stress, low predictability and
22
controllability of the environment by the animal should be prevented. At the same time,
positive emotions such as security, happiness and contentment should be aspired in
order to counterbalance negative events the animal may experience. Taken together,
promoting natural behaviours by taking into account the behavioural needs that an
animal has (Figure 1) is an important aspect of welfare which should be taken into
serious account when assessing and improving animal welfare. In the following section,
specific factors are discussed that influence welfare and welfare improvement in farm
animals, whereafter an overview will be given of current practices and their welfare
implications in cattle, pigs and poultry.
Figure 1: Examples of natural foraging behaviours in farm animals: grazing in cows, scratching and
pecking in chickens, and rooting in pigs (see section 3.2 through 3.4).
23
3 Farm animal welfare
3.1 Factors that influence farm animal welfare
3.1.1 Conflicting interests
Animals kept in husbandry practices have the disadvantage that their welfare is not the
only matter at stake, and often does not have the highest priority for men. There are
several stakeholders in the husbandry industry, with the main parties being the
consumer, the producer (farmer), the government and the animals (Webster 2001).
Whereas all human parties can convey their opinions, desires and can claim their rights,
the animals cannot, depending entirely on humans as to how they are treated and kept.
Although farm animals are generally believed to be sentient beings with some kind of
intrinsic value, they still depend on the value they are assigned by society, which mainly
treats them as mere agricultural products. The care and money people are willing to
spend on pet animals for example (Wise et al. 2003), is much greater than individual
farm animals receive, which is largely due to the value the animals have for us. However,
if we are to respect animals for their intrinsic value and truly care about their welfare,
their value to us should not be important. Welfare standards should not be different
whether the animal, for example a rabbit, is considered a plague, a pet, or a test animal:
its welfare needs remain the same (Webster 1994). Thus, not societal values, but the
subjective welfare perception and needs of the animal should determine welfare
standards.
What poses a problem in this idea, is that prioritizing animal welfare in farming
practices unavoidably imposes a costly impact on the other parties involved (although
improved animal welfare may also improve animal production, which eventually makes
extra costs profitable, see later in this chapter). Webster (2001) argues that humans are
mainly driven by self-interest, meaning that farmers will choose what the public desires
(as that is what creates profit for them), and the public generally wants high quality
animal products at low costs. Additionally, consumers have recently been taking an
interest in the welfare of farm animals, and are expressing their desire for a respectful
treatment and good quality of life for them. Between the two demands of low prices for
animal products on the one hand (self-interest) and high standards for animal welfare
on the other (moral values of animal treatment), lies a conflict. In a survey conducted
with English students, 76% of the respondents stated that they were concerned with the
24
poor welfare in husbandry practices, while only 34% ‘transferred this concern into
action by avoiding certain food products on animal welfare grounds’ (Bennett et al.
2002). Furthermore, 56% of the respondents believed that it was wrong to cause pain,
stress and injury to animals, while they still continued to eat meat. This indicates that
even within the consumers, there are conflicts of different interests and desires.
Raised concerns about the welfare of animals, but also about the safety of
production practices, are putting pressure on governments to adjust their policies
concerning farming practices. This is resulting in adjustments in policy making, as
economic efficiency and low food prices are no longer accepted to be the main priority
(Blandford & Fulponi 1999). Within the European Union for example, the Protocol on
Protection and Welfare of Animals states that members of the EU are ‘obliged to pay full
regard to the welfare of animals when formulating and implementing community
policies’ (Horgan 2006). The public expects the government to at least set minimum
standards for the treatment of animals to ensure unnecessary suffering is avoided.
Labelling products is a means of providing consumers information on production
methods, and, therefore, allows them to make a choice between systems that differ in
which welfare standards are applied. As reliable labelling demands traceability, higher
costs for the consumer are often the result (Blandford & Fulponi 1999).
In order to ensure whether safety and welfare standards are being met in
production systems, the government is additionally expected to regularly monitor and
inspect food production facilities. Over the past 50 years, many adjustments have been
made to farming systems in order to improve animal welfare, and regular surveillance is
being conducted (FAWC 2009). Furthermore, there is an emergence of financial support
offered to farmers that incorporate higher welfare standards (Horgan 2006). Animal
welfare is now incorporated in agricultural and veterinary education, as well as in
training programmes for farmers. Such education and communication about the
importance of welfare is necessary to change attitudes towards animals, in order to
increase the actual effect of stricter regulations (Forsberg 2011).
Thus, improving the welfare of farm animals is strongly dependent on public
concern, increased knowledge due to scientific research, farmers’ attitudes towards
animal welfare, and the willingness of governments to change policies and ensure the
effect of adjusted rules and regulations. All these factors complicate the actual
implementation of improving animal welfare.
25
3.1.2 Ethical concerns
Over many generations, farm animals have been genetically selected for high production
rates and reduced undesired behaviours. The emergence of genetic modification and
biotechnology has increased the deviation of farm animals from their natural ancestors.
A downside to this selection procedure is that as animals are selected for increased
production of meat and other products, undesired physiological and immunological side
effects arise (Rauw et al. 1998). This includes the occurrence of leg problems due to
increased growth rates, reduced reproduction rates and higher occurrence of diseases.
Thus, selection procedures for higher production rates impose side effects that cause
problems for animal welfare. The concern in this matter has little to do anymore with
the way these animals are kept and treated, as it is more a question of boundaries of
genetic selection procedures based on ethical grounds. Such ethical concerns can have
an impact on husbandry practices and policies. For example, in The Netherlands the
organisation Wakker Dier (‘awake animal’) launched a national campaign against
selecting and breeding broiler chickens for their fast growth, inducing injuries such as
sores and arthrosis, as well as problems with lung and heart functioning. Due to their
campaign, one of the largest suppliers of food and health products, Unilever, has
announced that they will stop using meat of these ‘bloated chickens’ in their products as
from the first quarter of 2013. Many supermarkets and companies such as McDonald’s
are now being pressured to follow their example.
Other practices that raise ethical concerns are therapeutic interventions. These
may be physical, such as tail-docking and beak trimming, or physiological, by the use of
antibiotics and drugs. Physical alterations reduce unwanted and harmful behaviours
such as aggression and redirected behaviours. Ethical concerns include the pain induced
by these practices, as they are often carried out unanestesized. In chickens, it is found
that beak trimming comprises some aspects of their welfare and is highly likely to
induce both acute and long-term pain (Cunningham 1992). The behaviour following
castration in lambs suggested that castration induces prolonged acute pain (Thornton &
Waterman-Pearson 2002). Such scientific findings on the adverse effects of these
practices on animal welfare raise ethical concerns, which can cause the modification of
these practices or force alternative practices to be developed (Swanson 1995).
Physiological interventions include the administration of drugs, antibiotics and
therapeutics that reduce unwanted behaviours. For example, adding tryptophan to the
26
diet of broiler chickens reduces their overall aggression levels (Shae et al. 1990).
However, the effect of farm animal drug administration on food safety and public health
should be investigated fully before such practices are applied on a large scale. As
mentioned before in section 2.2.2 on injury and disease, large-scale preventive
administration of antibiotics raise the concern of bacterial resistance, posing a problem
to both farm animal and human health (Gilchrist et al. 2007). Such ethical issues should
be addressed by studies focusing on the actual harmfulness of these practices, with
special focus on the implications for animal and human health. If animal welfare and
public health are not affected by these practices, communication to the public about the
safety and positive effects of such interventions is needed in order to prevent
misunderstandings that raise such concerns (Swanson 1995).
3.1.3 Housing systems
The design of housing systems can dramatically influence farm animal welfare. The
construction and maintenance of modern-day farm facilities are expensive, especially
when a large number of animals is being kept in the facility. Therefore, the animals kept
in such facilities often have limited space and are restricted in their movements
(Blandford & Fulponi 1999). Conventional systems are increasingly being adjusted in
order to meet the behavioural needs of the animal, ranging from increased enrichment
to alternative housing designs. Some simple adjustments to feeding methods such as
partitions and the use of automated feeding systems can reduce feeding aggression and
competition. Ernst et al. (2005) demonstrated a feeding system in which pigs are called
by a personal acoustic signal produced by a computer, after which they entered a
feeding station to receive food. Such a system both reduces feeding aggression and
serves as cognitive enrichment for the animals, thus improving their welfare in several
ways.
The effect of different housing systems on the welfare of animals is often assessed
by comparative studies. For example, comparison between four housing systems that
differed in their degree of calf confinement showed that high degrees of confinement are
associated with chronic stress in the calves (Dellmeier et al. 1985). In dairy cows, lying
down is a preferred behaviour as it facilitates rumination, and has been shown to
improve their health and reduce stress (see section 3.2.1). These findings have yielded
27
many studies on factors influencing lying behaviours, such as overcrowding (Fregonesi
et al. 2007) and stall surface material and dimensions (Tucker 2003).
One development in improving housing systems is the emergence of organic
farming systems, employing high standards of animal welfare and a restricted use of
drugs and pesticides. Although these systems are in general better for the welfare of the
animals, there are increased health risks due to outdoor access areas exposing the
animals to numerous infections, which may impose food safety problems to the
consumer (Kijlstra & Eijck 2006). Furthermore, the increased amount of space and care
given to the animals raises the prices of organic farming products as opposed to
conventional farming products. Thus, as mentioned before in section 3.1.1, prioritizing
animal welfare in alternative housing systems can cause inconvenient effects on other
parties involved, such as high costs for the farmer and consumer, and public health risks.
3.1.4 Farmer’s handling and attitude
Farm animals have one person they deal with daily: the person that cares for them. It
may not be surprising that the behaviour and attitude of the farmer towards his or her
animals has an impact on the animals’ welfare. Especially during early sensitization
periods does the handling of the farmer have a rather permanent effect on the later
behaviour of animals towards humans (Boissy & Bouissou 1988). This behaviour
consists of emotional responses due to recognition and anticipation. In a study
conducted with calves, regular contact reduced fear responses to transport and
handlings, and decreased the incidence of abomasal lesions (Lensink et al. 2000). In
sheep, it was shown that gentling reduced fear responses during subsequent handling,
showing that a change in attitude can also have an effect on animal behaviour later in
their life and on a short term (Hargreaves & Hutson 1990).
Not only does the attitude of the caretaker affect the welfare of the farm animals,
it has also been shown to affect their productivity. For example, sow farrowing rates,
reproductive performance and litter size were all influenced by stockperson’s attitude
and behaviour towards them (Hemsworth et al. 1989). Likewise, stockperson behaviour
influenced broiler chicken fear levels and productivity (Cransberg et al. 2000). Cows that
were handled by an aversive handler and a gentle handler showed an increased heart
rate and fear response to the aversive handler being present when milked, and an
increase of residual milk by 70% (milk that is not removed during milking) (Rushen et
28
al. 1999). Thus, the effect of the farmer’s attitude towards animals can have a
pronounced effect on not only the welfare of the animals, but also on their performance.
Adjustment of the attitude towards animals can therefore be beneficial for both the farm
animals and the farmer. Selecting stockpersons with certain behavioural and attitudinal
profiles, and increasing education towards stockholders, may help in changing their
attitudes towards the animals (Hemsworth et al. 1989).
3.1.5 Transport and slaughter practices
Transporting animals can severely reduce their welfare through high stress levels,
injuries and mortality. Moreover, this reduced welfare can have an impact on carcass
quality. Such injuries, bruises, morbidity, mortality and carcass quality can be used as
indicators of welfare during transport (Warriss 1998; Broom 2000). When transported,
animals are exposed to high amounts of novelty that they are often not accustomed to,
causing severe stress. This high level of stress is also due to low predictability and
controllability of the situation. Previous experience and genetic factors can influence
stress and fear responses to transport (Grandin 1997). Factors that most influence
stress responses during transport are loading and unloading of the animals, the
condition of the transport vehicle (such as climate condition and vehicle vibration), and
the characteristics of the journey (Trunkfield & Broom 1990). It is suggested that in
order to reduce stress levels during transport, mixing of groups should be avoided,
animals should be regularly checked during transport, and vehicle conditions should be
adequate and if possible, monitored throughout the journey (Hartung 2003). Moreover,
education and financial support to improve animal treatment by personnel handling the
animals during transport is suggested, as well as effective policies and control systems
(Hartung 2003; Hemsworth & Coleman 2011).
Much of public debates on the treatment of farm animals include debates about
slaughter and slaughter practices. Discussions often entail the very question whether
humans have the right to kill animals. However, as Broom (2011) argues, this is a
different ethical question in itself, which has little to do with the welfare of the animal.
Broom: ‘The animal welfare issue is what happens before death, including how they are
treated during last part of their lives, often the pre-slaughter period and then the
method by which they are killed.’ The conventional slaughter method that is used for
farm animals is stunning, in which a metal bolt is fired through the skull into the brain
(Troeger 2004). Alternative slaughter practices can reduce the amount of stress and
29
pain experienced by the animal, such as the use of gas mixtures in stunning practices
used in poultry (Raj 1998). Adjustments to slaughter practices are mostly due to
improvements of meat and carcass quality (Troeger 2004), although public concerns on
animal welfare have been of influence as well (Fletcher 1999).
3.1.6 Summary
All factors discussed in this section influence how animals are treated and how much
attention is given to their welfare. Education and financial incentives may alter the
behaviour of farmers towards their animals, which in turn can improve both the welfare
and the productivity of the animals. Labelling products and adjusting policies ensure the
consumer that husbandry practices are being monitored and welfare standards are
being set and controlled by the government. Eventually, good communication between
all stakeholders and respect for the needs and rights of all parties involved is likely to be
the most effective road towards improving animal welfare in husbandry practices
(Webster 2001).
In the following sections, I shall focus on the three most intensively farmed
animals worldwide (FAO 2011), being cattle, pigs and poultry. I will discuss their natural
behaviours and needs, briefly review common housing systems, and present a short
overview of practices and factors that influence their welfare.
3.2 Cattle
3.2.1 Dairy cows
Cows on free-range pasture spend most of their day grazing and lying down ruminating
(Table 1). Rumination is an important part of the feeding process in cattle, explaining
why cows have a strong behavioural need to lie down, which beside facilitating
rumination also serves the function of resting (Wieringa & Hopster 1990; Albright
1993). In stables, steel bars are commonly used in order to create separate lying cubicles
(Figure 2). These cubicles serve as a social barrier between cows: while on pasture cows
on average lie 2-3 meters apart from each other (Fraser & Broom 1990), in cubicles
separated by steel bars they will lie right next to each other (Potter & Broom 1987). The
design and dimensions of such cubicles is important, as problems with infections and
lying down / standing up behaviour can occur when cubicles are too short, too narrow,
neck rails are too low or stalls are not cleaned regularly (Veissier et al. 2004). In the
30
same study, it was found that cows prefer sand and deep litter over mattresses and
mattresses over mats and concrete as cubicle bedding material, which is accompanied
by a reduction of injuries. In general, soft surfaces are preferred by cows, on which they
spend more time lying down and which reduces injuries to the legs (Tucker & Weary
2001). Key welfare indicators in different housing systems include total lying time, lying
synchrony and cleanliness of the cows and the stable (Fregonesi & Leaver 2002; Veissier
et al. 2004).
Table 1: Time budget of cows on free-range pasture.
Behaviour
Grazing
Ruminating
Lying down
Hours performed per 24h
4 - 14
4–9
9 - 14
Source: Fraser & Broom 1990; Fregonesi & Leaver 2001
Eating with the head in a downward position as opposed to horizontal increases the
production of saliva with 17%, which, in turn, affects rumen function (McFarlane 1972).
Thus, feeding in stables generally occurs by offering feed on ground level (Figure 2).
Furthermore, providing feeding barriers in stables reduces differences in feed intakes
between socially high and low ranking individuals, which is shown to be due to
protection of the head by preventing physical contact (Bouissou 1970). Such innovations
both fulfill the behavioural needs of the cow and are beneficial for the farmer, as the
incidence of social conflicts, space requirements and feed intake differences are reduced.
However, feeding bars consisting of a simpler post-and-rail system as compared to
headlock feed barriers increases feeding time (Huzzey et al. 2006).
Figure 2: Lying cubicles (left) and feeding barriers (right) reduce social tension between cows.
31
Temperature and weather conditions can have pronounced effects on cow comfort and
performance when kept on pasture. Cows adjust their behaviour to weather conditions,
such as seeking shade on hot days, reducing their body temperature (Tucker
et al. 2007) and seeking shelter during heavy rainfall. The thermal neutral zone in cattle,
in which cows are able to regulate their body temperature and thus are comfortable, lies
between -35 and 25 degrees Celsius (Kadzere et al. 2002). Furthermore, cows are more
affected by heat than by cold (Hemsworth et al. 1995). In addition to the reduced
comfort experienced by the animal, excessive heat affects reproduction and lactation. In
a subtropical environment, Roman-Ponce et al. (1977) showed that providing shade
resulted in a 10% increase of milk yield and almost doubled conception rates from 25%
to 44%. Hence, providing shade during hot days or seasons can improve production and
reproduction rates. However, cows held on pasture often do not have any shade or
shelter available to them, as most cultivated land does not contain much, if any, trees or
other sources of shade or shelter. This can impose high levels of discomfort on days of
extreme weather such as prolonged periods of high temperatures or extensive rainfall.
Providing sources of shade can reduce such discomfort, thereby improving both welfare
and productivity.
Self- and allogrooming as well as scratching on other objects are believed to be
performed in order to maintain personal hygiene and thus reduce the occurrence of
infections and diseases. Therefore, trees may provide both a source of shade as well as
scratching surfaces, increasing welfare through stimulating multiple desired behaviours.
Furthermore, allogrooming forms and maintains social bonds in a herd (Sato et al.
1993). Social disruption such as mixing of groups increases aggression and social stress,
and has a strongly negative effect on feed intake and milk yield (Boe & Faerevik 2003).
Thus, the composition and dynamics of a social herd are important factors for the
welfare of cows. As mentioned before in section 3.1.4, farmer attitude and behaviour
towards the animals has an influence on cow behaviour and productivity (Breuer et al.
2000), with consistent milking procedures and predictable handling having a positive
effect.
Lameness and mastitis are the two major welfare problems in cattle. Lameness
can be defined as impaired movement or deviation from normal gait (Fraser & Broom
1990) and is associated with pain, reduced food intake, impaired body condition and
reduced milk production (Hemsworth et al. 1995, Warnick et al. 2001). There are
32
multiple causes of and factors influencing lameness, a few being housing design,
production rates, weather conditions, herd size and farmer behaviour (Hemsworth et al.
1995). More research is, however, still needed to fully elucidate which factors affect
lameness most. Mastitis is a bacterial infection causing inflammation of the mammary
tissue, resulting in abnormal milk and/or a hard or swollen udder. Bedding material and
practically any organic matter in the cow’s environment are sources of these bacteria
(Hogan & Smith 2003). Rates of infections are highest in the first two weeks after calving
(Shuster et al. 1996) and during milking procedures. Udder preparation prior to milking,
such as washing and drying, can reduce occurrence of infections considerably (Panky
1989). Risk factors of increased mastitis infections are the presence of cows within the
herd that are leaking milk or that have trampled teats, no disinfection of areas where
cows have calved, and continuous use of teat disinfection after milking (Elbers et al.
1998). Management practices such as frequent health controls and farmer skills and
motivation influence the identification of mastitis, which can result in timely and
adequate reaction to infections.
3.2.2 Calves
In common dairy practices, calves are isolated from the cow within 24 to 48 hours after
birth. Isolating the calf from the mother directly prevents a reduction of milk that can be
extracted from the cow, and reduces reactions in both cow and calf to separation as
opposed to later separation. However, separation at a later age improves sociality, later
maternal and reproductive behaviour, weight gain, productivity, health, and reduces
fearfulness in the calf (Flower & Weary 2003). Thus, later separation may eventually be
beneficial and counter-balance the negative behavioural effects that it causes, at least for
the farmer and the calf. The reason that young calves are in general isolated from other
calves is to prevent the transmission of pathogens, to which newborn calves are highly
susceptible. Another advantage of isolated housing is that the caretaker can easily
monitor the physical health and feed intake of each calf individually. Common housing
for isolated calves are calf hutches, in which they have free access to an in- and outdoor
area (Figure 3). Calves are housed individually during the first two weeks to prevent
navle-sucking of other calves when group-housed, and allow the navel to dry. A positive
effect of socially isolated rearing is that it increases milk production of the calf later in
life (Arave et al. 1985), although this may be due to the effects of chronic stress on
33
adrenocortical function (Creel & Albright 1988). The main negative issue is that social
interaction is prevented, which can cause the inability to develop normal social herd
behaviour later in life. For example, calves socially isolated for the first 8 months of their
lives had lower ranks and spent more time alone after being introduced into a herd,
compared to calves reared in groups (Broom & Leaver 1978). Group-housing has the
advantage that social behaviour is possible and space is increased, which in turn
increases the occurrence of play behaviour (Jensen et al. 1998). Play behaviour is seen
as an indicator of positive welfare, as such behaviour is only performed when all basic
needs are met (section 2.3.2). Pair-wise housing has no negative effects on physical
health and weight gain, and thus may be a good alternative to group-housing (Chua et al.
2002).
After separation from the cow, calves are fed artificial milk, which is often offered in
buckets. Providing milk in buckets causes a problem due to the strong behavioural need
of sucking in calves, as already mentioned in section 2.2.1. An alternative feeding
method is the use of artificial teats (Figure 4), which increases milk intake as the
behaviour is more reinforcing for the calf to perform than drinking from a bucket
(Hammell et al. 1988). Other influences on calf welfare include the environment, which
should be safe and clean, social herd behaviour, and interactions with the caretaker
(Stull & Reynolds 2008). Furthermore, as calves spend most of their time lying down,
the resting area should be clean and dry. Calf hygiene and the occurrence of lesions are
indicators of the cleanliness and comfort of the resting area, and therefore can be used
Figure 3: Calves housed in hutches have free access to an indoor and outdoor area, but are deprived of
social contact, causing abnormal social herd behaviour later in life.
34
Figure 4: Providing calves with artificial teats through which
they can obtain milk reduces problems that arise when fed
milk in buckets, due to their behavioural need to suck.
as indicators of calf welfare. Calves are affected by both heat and cold stress, being more
sensitive to both stressors than adult cows (Hemsworth et al. 1995).
Thus, thermal extremes should be avoided, pens should be safe and clean, and
calves should be regularly monitored for health problems in order to ensure their
welfare. Furthermore, later separation from the cow and pair-wise or group-housing
seems to have beneficial effects as opposed to direct removal and isolated rearing.
3.3 Pigs
3.3.1 Sows
A breeding facility for pigs, houses sows and their piglets up to around 25 kg, after
which piglets are transported to a finishing unit until slaughter age (unless both
facilities are combined in one location). In common practice, sows in breeding
facilities follow a continuous cycle of insemination, pregnancy and farrowing, which
is repeated after piglets are weaned. One week before the expected farrowing date,
sows are moved to farrowing crates (Figure 5), which have been designed to reduce
crushing of piglets by the sow (Marchant et al. 2000). Additionally, such crates make
piglet handling and management practices easier, reducing costs and dangers for
the farmer. However, much concern has been raised about the welfare of sows in
these farrowing crates, as they are restricted from all movements apart from
standing and lying down. This results in frustration behaviours in the sow (Rushen
1984), especially as the need for nest-building behaviours is strong before
35
farrowing, and this behaviour is prevented. Another problem arising in farrowing
crates is the difference in thermal requirements for sows and piglets. For sows,
temperatures of 15 – 26 degrees Celsius are comfortable, whereas new-born piglets
need much higher temperatures to stay warm, being 34 degrees or higher (Curtis
1995). This is often resolved by hanging a heat lamp under which piglets can huddle
together, increasing their body temperatures (Figure 5). There are several
developments of alternative farrowing systems, including outdoor-housing and
group-housing of sows throughout farrowing (Marchant-Forde 2009), although such
alternative systems raise costs due to bedding material and increased space, and are
more laborious for the farmer.
Between insemination and farrowing, sows are generally housed in groups.
Although there are still practices in which pregnant sows are confined individually,
this will no longer be permitted in the EU from January 2013 (Teagasc 2012). These
groups are often large, imposing problems e.g. for monitoring feed intakes and
feeding aggression. A feeding system that is now commonly used is electronic sow
feeding, where each sow carries an ear tag or collar with a responder, allowing her
access into the feeding station if she has not received her daily amount of feed yet
(e.g. Jensen et al. 2009). Although this solves the problem of monitoring individual
feed intake and reduces feeding aggression between sows, in natural circumstances
pigs eat in groups. Thus, such an individual feeding system prevents natural social
Figure 5: Sows in farrowing crates are restricted in their
movement, only being able to stand up and lie down. This
constriction results in frustration behaviours, especially
due to the prevention of nest-building behaviour.
36
feeding behaviour. A resulting problem is that aggression around feeding stations is
expressed in the form of vulva biting, which is one of the major welfare problems in
group-housed sows (Kroneman et al. 1993). This behaviour can be reduced by offering
roughage and creating subgroups of sows. Additionally, sows often deplete their entire
daily feed in one visit, imposing problems for foraging needs and strong feelings of
hunger the rest of the day (section 2.2.1). Other feeding systems include simultaneous
feeding in troughs that contain partitions (stimulating social eating while preventing
harmful contact), and individual feeding stalls (Marchant-Forde 2009).
In semi-natural circumstances, pigs spend about 75% of the day on foragingrelated activities (Stolba & Wood-Gush 1989), while domesticated pigs show only 1924% of this behaviour per day (Gonyou et al. 1992) and much time lying inactive
(Broom et al. 1995), both in individual and in group-housing. This difference may be due
to the lack of foraging material and space in domesticated pigs. In conventional sow
group-housing, flooring often consists of (partly or fully) slatted concrete, allowing
excrements to fall through. Such floors in general contain no bedding material,
preventing the sows to root and forage. In the EU, manipulable material must be
available if floors are not bedded. Slatted floors show a correlation with the incidence of
lameness, which is caused by foot problems such as lesions, osteochondrosis and
arthritis (Dewey et al. 1993). Factors that cause lameness are rapid growth and high
weight, floor characteristics (slipperiness, hardness, cleanliness), season, type of
housing system and management practices (Kroneman et al. 1993). General measures of
welfare in sows include the incidence of stereotypies and other abnormal behaviour,
reproductive problems, body functions, physical health and stockperson management
(Marchant-Forde 2009).
3.3.2 Growing-finishing pigs
After weaning, pigs are regrouped and raised on breeding facilities to around 25 kg,
after which they are transported to a finishing facility where they are raised until
slaughter age. Weaning is very stressful for the young piglet (3-4 weeks) as it is
accompanied by a change of diet and location, separation from the mother, and mixing
with unfamiliar conspecifics; all causing stress (Gentry et al. 2008). This stress can be
reduced by familiarising the new environment using elements of the pre-weaning
37
period, such as maternal pheromones and enrichments from the farrowing
environment. Additionally, Pitts et al. (2000) showed that mixing at very young ages
reduces fight durations and results in 80% fewer injuries from fighting. Thus, mixing in
the pre-weaning phase can reduce aggression and stress after weaning.
Transport towards and mixing at the finishing facility is another source of stress
for growing-finishing pigs (Coutellier et al. 2007). Intensive finishing facilities commonly
house pigs in large groups in inside pens, which are often barren environments with
stationary feeders (Figure 6). The emergence of such housing systems is caused by
maximising production efficiency, resulting in decreased space per pig, automated
feeding systems and widespread use of slatted floors (O’Connell 2009). Adjusting such
systems in order to improve welfare by allowing the pigs to perform natural behaviour
and have more space, implies more costs to both the farmer and, eventually, the
consumer (section 3.1.1). Some alternative housing systems include the provision of
bedding material and systems in which lying areas are separate from excretory areas
(SVC 1997). Providing bedding material can both reduce injuries, e.g. due to reduced
slipperiness, and offer enrichment by stimulating natural foraging behaviour (Studnitz
et al. 2007). Additionally, pigs show a preference for pens with substrate over concrete
(Beattie et al. 1998). Barren environments prevent pigs from performing foraging
behaviour such as rooting, resulting in harmful redirected behaviours such as tail biting
and aggression. This is especially the case if space allowance per pig is decreased
(Turner et al. 2000). Furthermore, offering rooting material increases the incidence of
play behaviour (Beattie et al. 1996), which as previously discussed in section 2.3.2 is an
Figure 6: After weaning and until slaughter age, piglets
are commonly housed in barren environments in large
groups, causing problems such as redirected behaviours.
38
indicator of positive welfare. Straw is the most suited enrichment material when pig
welfare, economics and practicality are all considered (van de Weerd & Day 2009).
Important factors of influence on the welfare of growing-finishing pigs are
physical health, stockmanship interactions (quality and quantity), type of housing
system, and management practices (Gentry et al. 2008). Environmental enrichment and
improved handling by caretakers are areas of possible improvement of pig welfare.
3.4 Poultry
Compared to other farm animals, chickens belong to an entire different class of species,
with different anatomy and physiology, and, therefore, different welfare problems. Being
birds, the biggest differences with mammals are that they are feathered, have beaks, and
that they lay eggs. Birds are sensitive to hypothermia due to their high body
temperature and high metabolic rate. Furthermore, birds have a more complex
respiratory system, making them vulnerable to polluted air. The condition of their
plumage is an important aspect of their welfare (Cooper & Cooper 2010). Chickens are
perching birds, meaning that their feet are anatomically suited to clasp around branches
of trees. Perching is a desired behaviour in chickens, which can promote the feeling of
safety due to the possibility to escape to higher grounds (Figure 7; Newberry et al.
2001). When allowed, chickens will walk 1 to 1.5 km per day and frequently fly to and
from elevated places (Keppler & Fölsch 2000). This distance is reduced in systems
without free range. Dustbathing belongs to the natural behaviour of chickens, which
serves the function of keeping their plumage in good condition (Figure 7; van Lier &
Figure 7: Perching (left) is a desired behaviour in chickens, giving them a feeling of safety and the ability
to express natural behaviour. Dustbathing (right) keeps plumage in good condition and appears to be
pleasurable for chickens to perform.
39
Bokma 1987). Furthermore, the behaviour itself is likely to be pleasurable to perform
(Widowski & Duncan 2000). The analysis of foraging behaviour in Red Junglefowl (wild
ancestor of the chicken) in a semi-wild environment showed that 60% of the time was
spent pecking and 34% ground scratching (Dawkins 1989). The inability of expressing
such foraging behaviour results in redirected behaviours such as feather pecking and
cannibalism (Blokhuis & Wiepkema 1998; Huber-Eicher & Wechsler 1998), of which the
harmful consequences are reduced by beak trimming. However, the frustration within
the bird resulting from not being able to express natural foraging behaviour remains the
same when its beak is trimmed. Thus, beak trimming does not solve the problem of
frustration in the animal resulting from not being able to perform desired foraging
behaviour. Moreover, beak trimming is likely to be accompanied by acute and long-term
feelings of pain (Cunningham 1992). Housing systems where chickens are housed inside
often contain large amounts of chickens in an artificially lit space in which temperature
and air quality are controlled by automated systems. Artificial lighting regimes are often
used to stimulate egg or meat production.
There are two resources for which chickens are being kept in husbandry
practices, being eggs of laying hens, and meat of broiler chickens. Therefore, laying hens
and broiler chickens are kept under different circumstances, which are both shortly
reviewed here.
3.4.1 Laying hens
In battery cages (Figure 8), chickens have little space and no litter material to perform
foraging or dustbathing behaviour in. Battery cages generally consist of small wire mesh
cages that house 3 to 6 hens per cage. The cage is often just high enough for the chicken
to stand up right, and the wire mesh bottom contains a slight slope, causing eggs to roll
to the front of the cage for collection (Sherwin 2010). The emergence and popularity of
battery cages among producers has been due to economic efficiency and high levels of
production. However, these conditions result in strong physical and physiological
discomfort and frustrations in the hens, as natural behaviours cannot be performed and
social stress is high. Moreover, laying hens raised in cages are not able to move much,
which reduces their bone strength and makes them more susceptible to leg problems
40
Figure 8: Left: hens in battery cages. Right: hens in barn systems do not necessarily offer chickens more
space than battery cages, although they may offer perches and nest boxes, stimulating natural behaviour.
than chickens raised in alternative systems, such as perchery and terrace systems
(Knowles & Broom 1990). Battery cage systems have been criticised to such an extent
that they were banned in the EU in 1999. After a 12-year phase-out period, the ban has
been effective as from January 1st 2012.
Alternative systems that are now increasingly used are enriched cage systems,
barn systems and free-range systems. Any system generally still suffers from problems
with overcrowding, as in barn systems in which chickens are kept with thousands
individuals in one flock (Figure 8). Increased densities and thus reduced space per hen
in cage systems is correlated with higher mortality, decreased egg laying, and reduced
food consumption (Adams & Craig 1985). When chickens are offered increased space
after being confined, they show rebound behaviour including wing flapping, stretching
and tail wagging (Nicol 1987), indicating that confinement prevents natural, desired
behaviours. Enriched or get-away cages contain increased space per chicken, perches,
nest boxes and litter material, which are minimum EU requirements since battery cages
have been banned. All these features improve the hen’s welfare, making it possible to
express at least some natural behaviours such as wing flapping, perching and using a
nest box for egg-laying. Cage dimensions can differ, housing small groups of 4-8, or large
groups of 60-80 hens. Although labour and costs to the farmer are slightly increased, the
possibility of expressing natural behaviour increases the welfare of the hen considerably
(Wegner 1990). In barn systems, chickens are kept in a barn in one large flock, which is
typically around 15,000 with a maximum of 25 chickens per m2 in the EU (Sherwin
2010). When flooring material consists of deep-bedded sawdust or any similar bedding
material, the system is referred to as deep-litter. Litter material allows hens to
41
dustbathe, peck and scratch, although substrate preferences differ for foraging
behaviour and dustbathing behaviour (Scholz et al. 2010). Most barn systems contain
nest boxes, and may contain perches or shelves. However, these systems are not
required to offer perches, dustbathing substrate or nest boxes, and do not necessarily
offer more space per hen than cage systems (BCSPCA 2009). If litter is provided and its
condition monitored and maintained, this can reduce foot problems in the hens. Freerange systems include access to an outside area, which usually includes vegetation and
provides overhead shelter. The inside housing of such systems generally contains
perches and nest boxes. Flock size typically ranges from 7,000 to 15,000 and space per
hen in free-range systems is again not necessarily increased compared to cage systems.
Although welfare is increased in alternative systems, no system is ideal in terms of hen
welfare. No-cage systems, although they offer more freedom of movement, increase the
risk of diseases and harmful redirected behaviours compared to cage systems. It is
believed that housing small groups of hens, combined with enrichment and freedom of
movement would be the most ideal housing system in terms of hen welfare (Appleby &
Hughes 1991).
Mortality in laying hens is influenced by season, feather colour (with white hens
showing less mortality), country and kind of system (Blokhuis et al. 2007). Furthermore,
groups of non-beak trimmed chickens showed more mortality due to cannibalism and
redirected feather pecking. In short, hen welfare is influenced by space per hen, the
ability to perform natural behaviours such as perching and the use of nest boxes, and
redirected behaviours of conspecifics. Additionally, hygiene, air quality and health
influence their welfare (Jendral 2005). Increased human contact reduces stress caused
by handling, and increases egg-production (Barnett et al. 1992).
3.4.2 Broiler chickens
Broiler chickens are raised for meat production, which has subjected them to intensive
genetic selection for fast growing rates. There are three components of the broiler
production system, consisting of broiler-breeder farms, hatcheries and broiler-growing
farms (NASS 2005). At broiler-breeder farms, mature hens and roosters are kept
together for about one year, for natural fertilization of the eggs. The eggs (around 300
per hen per year) are collected and moved to a hatchery for incubation. After hatching,
chicks are vaccinated and transported to a broiler farm, usually within 24 hours of
42
hatching. At the broiler farm, chickens follow a growing cycle, in which the entire flock of
chickens is raised until slaughter weight (2 – 4 kg,), which may be reached between 5
and 8 weeks of age, depending on the market for which the bird is raised. The indoor
barn system is most commonly used in broiler chicken housing, containing a deeplittered floor which is replaced after disinfection of the barn between cycles, to prevent
the spreading of diseases between flocks. Furthermore, barn systems contain automated
feeding (ad libitum to maximize growth) and water systems (Figure 9). Feeding may be
restricted during early life to reduce incidences of metabolic disorders (Acar et al.
1995). Temperature, ventilation and lighting are carefully controlled from day-old to
slaughter age. Broiler chickens are often kept under continuous or 23 hour lighting
periods in the first few days, promoting feeding and thus growth rates (Widowski 2010).
This can significantly impair their welfare as they have little time to rest compared to
natural day-night conditions, and are thus unable to develop a normal circadian rhythm.
Light intensity is gradually decreased upon aging, minimizing activity but bright enough
for the chickens to find food and water. Stocking densities depend on slaughter weight
and typically range from 25 to 40 kg/m2 (Meluzzi & Sirri 2009). Litter quality is an
indication of management practice quality, as damp or dirty litter may result in breast
blisters and other welfare problems. Good litter provides insulation from cold floors, is
absorbent and forms a proper environment for bacteria to convert excrements into drier
products. Furthermore, good litter material keeps birds clean and minimizes dust
problems. Most commonly used litter materials are soft wood shavings, chopped straw
and bark chips. In a preference-choice test, it was found that broiler chickens spent most
time on sand and wood shavings, and least on rice hulls and recycled paper roll
(Toghyani et al. 2010). Furthermore, they spent more time dustbathing on sand. Litter
Figure 9: Broiler chickens in a conventional barn system.
43
material had no effect on performance, although it may be argued from the results of the
preference test that sand and wood shavings stimulate natural behaviour, and thus
increase broiler chicken welfare.
Alternative housing systems are semi-intensive and free-range systems. Semiintensive housing systems allow access to an outside run, and are shown to increase
meat and carcass quality (Castellini et al. 2002). Welfare in these systems is improved by
reduced stress-levels and increased activity, caused by increased space per chicken.
Slaughter age is increased in semi-intensive housing systems (up to 10 weeks), as
growth rates are lower than in conventional systems (Brown et al. 2008). Free-range
systems house chickens at lower stocking densities than conventional systems. After
three to four weeks, access to pasture is allowed. Use of this pasture and perches is often
reduced due to leg problems (Weeks et al. 1994), which is one of the main welfare
problems in broiler chickens (FAWC 1992). Compared to free-range and semi-intensive
housed chickens, meat taste and tenderness was judged to be better from chickens
raised under standard conditions by a taste panel (Brown et al. 2008). Such findings may
hamper the transition from standard to alternative housing systems. Climatic conditions
have a greater impact on welfare than does stocking density, with temperature and
humidity being the most important factors influencing mortality (Dawkins et al. 2004).
In broiler-breeding flocks, feed is severely restricted in order to reduce growth
and prevent problems with egg production and fertility (Mench 2002). However, as
broiler breeds have been genetically selected to always be hungry (increasing their food
intake and thus growth rates), this results in extreme, chronic hunger and high levels of
stress in broiler-breeding hens (Hocking et al. 1993). Alternative methods that have
been developed have proven unsatisfactory, thus there is still a strong need for
developing alternatives to current food restriction programmes in order to improve
broiler-breeder welfare.
Read-out parameters of broiler chicken welfare are mortality rate, gait, physical
health, plumage condition, growth rate, lameness, carcass and meat quality, and
behaviour (Dawkins et al. 2004; OIE 2009). Such behavioural welfare indicators include
natural behaviours such as dustbathing, human-avoidance behaviours, thermal stress
behaviours (panting and wing-spreading), and redirected behaviours such as
cannibalism and feather pecking. Farmer behaviour influences fear levels in broiler
chickens and productivity, possibly due to chronic stress (Cransberg et al. 2000).
44
4 Discussion
4.1 Addressing farm animal welfare
The issue of animal welfare is a complex one. Not only is it difficult to capture what the
term ‘welfare’ exactly entails as it is subject to the influence of personal values and
ethics (Hewson 2003), what should be done about the welfare of animals is another
difficult matter. For our pet animals, we are willing to invest large amounts of time,
energy and money to give them a good life (Wise et al. 2003). They offer us company and
pleasure, which makes us feel obliged to treat them with love and respect. For farm
animals however, the balance of the human-animal bond is different. As they provide us
with resources that we consume, their ‘services’ to us are often less personal. Moreover,
the exponential global increase of animal product consumption due to the expansion of
our species (FAO 2006), is increasing the distance between the consumer and the
animal. Many consumers are unaware of the exact methods that precede the production
of the piece of meat they buy at the supermarket (Eurobarometer 2007). It may be at the
interest of some farmers to keep consumers unaware of these practices, in order to keep
producing profitable. The demand of consumers for humane treatment of animals, while
at the same time demanding low prices for good quality animal products, puts a great
burden on producers. We must realize that there is controversy in these two demands
within the consumer. Allowing all hundreds of millions of farm animals worldwide (FAO
2009) all the space and freedom they would prefer, would raise the costs of animal
products considerably (let alone if it would be practically possible). Therefore, we must
be reasonable when addressing the improvement of farm animal welfare. In the words
of Marchant-Forde (2009): ‘It is all too easy to judge intensive farming practices, when
we consider only the welfare of animals within a given system. We have to consider the
bigger picture and balance the positive and negative aspects that intensive agriculture
has on our society as a whole, before reaching a decision about overall acceptability of a
given husbandry practice.’
4.2 Influence of scientific research
Scientific research on animal physiology and behaviour has increased awareness and
understanding of how animals subjectively perceive the world around them. Findings on
negative emotions such as stress and fear, but also the recently emerged field of
research on positive emotions such as play and social behaviour, is gradually changing
45
our view on animals and their welfare. The resulting knowledge is important, or even
crucial, in welfare assessment. As Hewson (2001) states: ‘Whatever we decide about
animal welfare as a profession or as individuals, we must be knowledgeable.’ Only when
we know which effects our actions have on the animal (species), we can decide to what
extent we find our actions acceptable. Still, all research on animal physiology, behaviour,
emotions and feelings will never fully answer the question of how an animal truly
experiences its life. As Boissy et al. (2007) argue: ‘Given the very nature of emotional
self-experience, there is ultimately no way to know if animals experience emotions
similar to humans.’ In fact, to measure emotions and feelings in individual humans has
already proven to be very difficult, let alone in animals. Research on physiological,
neurological and behavioural reactions which can be linked to emotions, such as
increased heart and respiration rates and dilated pupils when stressed or fearful, has
shown many analogies between humans and other animals (section 2.2.3, Bateson
1991). Such findings in combination with the fact that humans share an evolutionary
ancestor with other mammals, support the idea that animal analogies of human
emotional responses can be used for the assessment of animal emotions and welfare.
Although this can bring us close to an idea of how the animal experiences its
surroundings and conditions it is living in, it will ever tell us how the animal truly
perceives life. Therefore, science cannot provide us with the full answers that we search
for in animal welfare research and assessment, which is why we must allow common
sense and experience with animals to contribute to the decisions we make. This is where
ethical values come into play and may provide a useful contribution, as different parties,
through discussions and considerations, can indicate which practices they find
(un)acceptable and why. Such ethical discussions may fill the gaps that science leaves us
with in the hard-to-assess matter that welfare currently is.
The European Union funded project Welfare Quality was founded in 2004, its goal
being to develop a European standard on farm animal welfare. It has since developed
reliable tools for assessing and monitoring the welfare of farm animals both on the farm
and at slaughter. This project provides useful tools to gain reliable information on
animal welfare for consumers, farmers, and regulators. Such projects provide essential
starting points to address the assessment and regulation of animal welfare.
46
4.3 Complexity of the issue of farm animal welfare
Eventually, the farm animal welfare debate is one between and among biologists,
philosophers, ethologists, farmers, veterinarians, politicians, agricultural engineers,
consumers and non-consumers (vegetarians and vegans). It is important to realize that
this debate brings together groups of people with vastly different interests, beliefs and
backgrounds. If we are to come to a sustainable solution, all these different groups of
people must be able to respect each other’s needs, desires and interests. The farmer is to
respect the public that raises concern about the welfare of farm animals, and the needs
of his animals; the government is to respect the wishes of the public and of the farmer; et
cetera. Moreover, all parties involved should realize that farm animals have no voice in
this debate, though they are the ones that are compromised the most. Therefore, farm
animals rely on the empathy and willingness of humans to take the matter of their
welfare serious. For all the resources that these millions of animals provide to us, they
deserve at least some reciprocity in the form of respect, and an effort to give them a
reasonably good quality of life. In essence, I argue that we should stop raising farm
animals as if they are merely producers of meat, milk and eggs, and start to fully realize
that they are live animals with emotions, expectations, subjective feelings and personal
experiences. In order to respect them as individual beings, we ought to provide animals
with an interesting environment that allows them to behave normally and feel secure
(Hawkins 2010). Furthermore, complying to their wishes does not have to be a difficult
or expensive task to accomplish. There are numerous ways to improve at least some
aspects of the lives of farm animals. Small adjustments or additions that allow them to
express desired behaviours can reduce boredom and increase pleasurable feelings in the
animals, which in turn can improve health and production rates (section 3.2 through
3.4). Kind and patient handling, especially during the early phase of their lives and
during stressful situations, reduces fear and chronic stress. This again in turn improves
health and production (section 3.1.4). Such small adjustments to common practices thus
can result in benefits for more stakeholders in the industry than the animals alone.
Increased health and production is beneficial for the farmer, whereas a better treatment
of animals will improve the image of farming practices that consumers have. If
governments ensure that regulations are followed through by regularly monitoring
farms, and help farmers to improve their practices and procedures by offering education
and incentives, this may further accelerate the improvement of farm animal welfare.
47
Thus, within reasonable boundaries of the industry’s complexity, we can realize changes
that can be beneficial for multiple stakeholders. For example, providing covering for
cows kept at pasture offers them shade and shelter from unpleasant weather conditions,
improving both their welfare, milk yield and reproduction rates (section 3.2.1; RomanPonce et al. 1977). The provision of shelter need not be expensive, making it relatively
easy to address this matter. Another example is the enriched cage system for laying hens
(section 3.4.1), which allow them to perch and use nest boxes for egg laying. Besides
improved welfare for the chickens, the desire of consumers to improve animal welfare is
heeded, and raised costs to the farmer are reasonable. As Moura et al. (2006) argue
about broiler chickens: ‘It is known that the result of a broiler not adequately housed is a
direct loss in production which leads towards a thought that health, welfare and
productivity are intimately connected.’ This connection between welfare and
productivity is an important finding, which may help convince farmers that a better
treatment of and enriched housing for their animals may be beneficial to themselves as
well. Moreover, if it is communicated to consumers that raised prices for animal
products are due to improved animal welfare, they may be more willing to pay a higher
price. It takes innovation and willingness to address these issues and come to solutions
that take into account all stakeholders’ interests, including those of the animals.
Eventually, all parties involved must take some responsibility and make an effort to
understand and respect each other in the matter of animal welfare improvement, in
order to come to an effective and sustainable solution (Mench & van Tienhoven 1986;
Webster 2001).
For example, Wageningen University & Research centre in The Netherlands has
brought together ideas and desires of farmers and consumers, combined with
behavioural research on chickens, in order to develop a system that satisfies animals,
consumers and farmers. One of the outcomes of this ‘Keeping and Loving Hens’ project,
is the Rondeel farming system. The eggs of this farming system are now famous for their
high welfare standards while being priced reasonably, and are being sold in the biggest
chain of supermarkets in The Netherlands, Albert Heijn, since june 2010.
4.4 Concluding remarks
In the past 50 years, great developments that have improved farm animal welfare have
taken place, especially in the EU (Horgan 2006; FAWC 2009). Slowly but surely, farming
practices that result in bad animal welfare are being prohibited by law, indicating a
48
strong trend that animal welfare is becoming increasingly important to the public and,
consequently, their governments. Additionally, the amount of scientific literature on the
improvement of the lives of farm animals is increasing rapidly. This scientific research
on animal welfare is, however, still in its infancy, and although global interest in the field
is increasing, more research is still much needed. For current developments to reach
their objectives, several factors are of influence. First, governments must set minimum
welfare standards in collaboration with the scientific field, society and the farming
industry. Furthermore, they should act as an agent protecting the rights of animals, by
ensuring that rules are being maintained. Communication to the public is important in
this matter, which can be achieved through reliable labelling of animal products,
communication and education. Second, scientists should continue to elucidate animal
functioning, preferences and effects of our handling on their welfare, making welfare
assessment easier and more reliable. Third, farmers should be willing to continuously be
educated about their animals and the effects that their behaviour and attitude has on
them. Fourth, consumers should be aware that their desires are in conflict, which may be
one of the most influencing factors in improving animal welfare. When consumers are
willing to pay for the improved welfare of farm animals that they desire, which may
either imply a reduction of animal product consumption or increased expenditure, it can
be possible to meet their conflicting demands. However, once there are no cheaper
alternatives due to regulations and policies excluding practices that result in bad
welfare, the consumer will have to pay more for animal products as they have no choice.
It is the interplay between all these factors and conditions that determine the
future success and pace of farm animal welfare improvement (FAWC 2009). With the
right amount of effort and willingness of all stakeholders, it will be possible to make a
difference. In the end, living in harmony with the animals we keep can help to realize a
stable and durable human-animal relationship. Our mentalities and attitudes towards
animals and their welfare are slowly changing, and it is only when we allow this
paradigm to shift that we will reach the goals we desire to achieve in animal welfare.
Luckily, there is an increasing number of people that care and are willing to make an
effort to make that change.
49
50
5 References
Acar N., Sizemore F.G., Leach G.R., Wideman R.F., Owen R.L., Barbato G. 1995. Growth of
broilers in response to feed restriction regimens to reduce ascites. Poultry Science 74:
833 – 843.
Adams A.W., Craig J.V. 1985. Effect of crowding and cage shape on productivity and
profitability of caged layers: a survey. Poultry Science 64: 238 – 242.
Albright J.L. 1993. Feeding behavior of cattle. Journal of Dairy Science 76: 485 – 498.
Appleby M.C., Hughes B.O. 1991. Welfare of laying hens in cages and alternative systems:
environmental, physical and behavioural aspects. World's Poultry Science Journal 47: 109
– 128.
Arave C.W., Mickelsen C.H., Walters J.L. 1985. Effect of early rearing experience on subsequent
behavior and production of Holstein heifers. Journal of Dairy Science 68: 923 – 929.
Barnard C.J., Hurst J.L. 1996. Welfare by design: the natural selection of welfare criteria. Animal
Welfare 5: 405 – 433.
Barnett J.L., Hemsworth P.H., Newman E.A. 1992. Fear of humans and its relationships with
productivity in laying hens at commercial farms. British Poultry Science 33: 699 – 710.
Bateson P. 1991. Assessment of pain in animals. Animal Behaviour 42: 827 – 839.
BCSPCA. 2009. The housing of egg-laying hens. The British Columbia Society for the Prevention
of Cruelty to Animals. Available at http://www.spca.bc.ca/welfare/farm-animal-welfare/
Beattie V.E., Walker N., Sneddon I.A. 1998. Preference testing of substrates by growing pigs.
Animal Welfare 7: 27 – 34.
Beattie V.E., Walker N., Sneddon I.A. 1996. Effects of environmental enrichment on behaviour
and productivity of growing pigs. Animal Welfare 4: 207 – 220.
Bennett R.M., Anderson J., Blaney R.J.P. 2002. Moral intensity and willingness to pay
concerning farm animal welfare issues and the implications for agricultural policy.
Journal of Agricultural and Environmental Ethics 15: 187 – 202.
Blackshaw J.K., Swain A.J., Blackshaw A.W., Thomas F.J.M., Gillies K.J. 1997. The
development of playful behaviour in piglets from birth to weaning in three farrowing
environments. Applied Animal Behaviour Science 55: 37 – 49.
Blandford D., Fulponi L. 1999. Emerging public concerns in agriculture: domestic policies and
international trade commitments. European Review of Agricultural Economics 26: 409 –
424.
Blokhuis H.J., van Niekerk T.F., Bessei W., Elson A., Guémené D., et al. 2007. The LayWel
project: welfare implications of changes in production systems for laying hens. World’s
Poultry Science Journal 63: 101 – 114.
Blokhuis H.J., Wiepkema P.R. 1998. Studies of feather pecking in poultry. Veterinary Quarterly
20: 6 – 9.
Boe K.E., Faerevik G. 2003. Grouping and social preferences in calves, heifers and cows. Applied
Animal Behaviour Science 80: 175 – 190.
Boissy A., Manteuffel G., Jensen M.B., Moe R.O., Spruijt B., et al. 2007. Assessment of positive
emotions in animals to improve their welfare. Physiology & Behavior 92: 375 – 397.
Boissy A., Bouissou M.F. 1988. Effects of early handling on heifers' subsequent reactivity to
humans and to unfamiliar situations. Applied Animal Behaviour Science 20: 259 – 273.
Bondi A.A. 1987. Animal nutrition. Magnes Press, Hebrew University, Jerusalem, Israel.
Borg K. E., Esbenshade K. L., Johnson B. E. 1991. Cortisol, growth hormone and testosterone
concentrations during mating behavior in the bull and boar. Journal of Animal Science 69:
3230 – 3240.
Bouissou M.F. 1970. Rôle du contact physique dans la manifestation des relations hiérarchiques
chez les bovins: conséquences pratiques. Annales des zootechnie 3: 279 – 285.
Bracke M.B.M., Hopster H. 2006. Assessing the importance of natural behavior. Journal of
Agricultural and Environmental Ethics 19: 77 – 89.
51
Bracke M.B.M, Spruijt B.M., Metz J.H.M. 1999. Overall welfare reviewed. Part 3: Welfare
assessment based on needs and supported by expert opinion. Journal of Agricultural
Science 47: 307 – 322.
Bradshaw J.W.S., Nott H.M.R. 1995. Social and communication behaviour of companion dogs.
In: Serpell J. (ed) The domestic dog: its evolution, behaviour, and interactions with people.
Cambridge University Press.
Brambell Report. 1965. Report of the Technical Committee to enquire into the welfare of
animals kept under intensive livestock husbandry systems. Her Majesty’s Stationery
Office, London, UK.
Breuer K., Hemsworth P.H., Barnett J.L., Matthews L.R., Coleman G.J. 2000. Behavioural
response to humans and the productivity of commercial dairy cows. Applied Animal
Behaviour Science 66: 273 – 288.
Brody S. 1956. Climatic physiology of cattle. Journal of Dairy Science 39: 715 – 725.
Broom D.M. 2011. A history of animal welfare science. Acta Biotheoretica 59: 121 – 137.
Broom D.M. 2000. Welfare assessment and welfare problem areas during handling and
transport. In: Grandin T. (ed), Livestock Handling and Transport. Department of Animal
Science, Colorado State University, Colorado, U.S.A.
Broom D.M. 1988. The scientific assessment of animal welfare. Applied Animal Behaviour
Science 20: 5 – 19 .
Broom D.M. 1986. Indicators of poor welfare. British Veterinary Journal 142: 524 – 526.
Broom D.M., Leaver J.D. 1978. Effects of group-rearing or partial isolation on later social
behaviour of calves. Animal Behaviour 26: 1255 – 1263.
Broom D.M., Mendl M.T., Zanella A.J. 1995. A comparison of the welfare of sows in different
housing conditions. Animal Science 61: 369 – 385.
Brown S.N., Nute G.R., Baker A., Hughes S.I., Warriss P.D. 2008. Aspects of meat and eating
quality of broiler chickens reared under standard, maize-fed, free-range or organic
systems. British Poultry Science 49: 118 – 124.
Burgdorf J., Panksepp J. 2006. The neurobiology of positive emotions. Neuroscience and
Biobehavioural Reviews 30: 173–187.
Byers J.A., Walker C. 1995. Refining the motor training hypothesis for the evolution of play.
American Naturalist 146: 25 – 41.
Cabanac M. 1971. Physiological role of pleasure. Science 173:1103 – 1107.
Castellini C., Mugnai C., dal Bosco A. 2002. Effect of organic production system on broiler
carcass and meat quality. Meat Science 60: 219 – 225.
Chan W.Y. 2011. The meaning of barks: vocal communication of fearful and playful affective
states in pigs. Dissertation, Department of Animal Sciences, Washington State University.
Chen L.Y., Chen L.K., Chang C.W., Kuo S.C., Li L.F., Chan Y.J., Wang F.D. 2012. Treatment of
community-onset methicillin-resistant Staphylococcus aureus (MRSA) bacteremia: A
hospital-based study. Archives of Gerontology and Geriatrics 55: 152 – 156.
Chua B., Coenen E., van Delen J., Weary D.M. 2002. Effects of pair versus individual housing on
the behavior and performance of dairy calves. Journal of Dairy Science 85: 360 – 364.
Cooper J.E., Cooper M.E. 2010. Chapter 1: Introduction. In: Duncan I.J.H., Hawkins P. (eds):
Welfare of domestic fowl and other captive birds. Animal Welfare Volume 9, Springer.
Cooper J.J., Mason G.J. 2001. Increasing costs of access to resources cause re-scheduling of
behaviour in American mink (Mustela Vison): implications for the assessment of
behavioural priorities. Applied Animal Behaviour Science 66: 135 – 151.
Cooper J.J., Mason G.J. 2000. The use of operant technology to measure behavioral priorities in
captive animals. Behavior Research Methods, Instruments, & Computers 33: 427 – 434.
Coutellier L., Arnould C., Boissy A., Orgeur P., Prunier A., Veissier I., Meunier-Salaün M.C.
2007. Pig’s responses to repeated social regrouping and relocation during the growingfinishing period. Applied Animal Behaviour Science 105: 102 – 114.
Cransberg P.H., Hemsworth P.H., Coleman G.J. 2000. Human factors affecting the behaviour
and productivity of commercial broiler chickens. British Poultry Science 41: 272 – 279.
52
Creel S.R., Albright J.L. 1988. The effects of neonatal social isolation on the behavior and
endocrine function of Holstein calves. Applied Animal Behaviour Science 21: 293 – 306.
Crespi L.P. 1942. Quantitative variation in incentive and performance in the white rat. American
Journal of Psychology 40: 467 – 517.
Crowell-Davis S.L., Curtis T.M., Knowles R.J. 2004. Social organization in the cat: a modern
understanding. Journal of Feline Medicine and Surgery 6: 19 – 28.
Cunningham D.L. 1992. Beak trimming effects on performance, behavior and welfare of
chickens: a review. Journal of Applied Poultry Research 1: 129 – 134.
Curtis S. E. 1995. The physical environment and mortality. In: M. A. Varley (ed.) The neonatal
pig. Development and survival. CAB International, Wallingford, Oxon, U.K. p 269 – 285.
Dawkins M.S. 1990. From an animal’s point of view: motivation, fitness and animal welfare.
Behavioral and Brain Sciences 13: 1 – 61.
Dawkins M.S. 1989. Time budgets in Red Junglefowl as a baseline for the assessment of welfare
in domestic fowl. Applied Animal Behaviour Scien ce 24: 77 – 80.
Dawkins M.S., Donnelly C.A., Jones T.A. 2004. Chicken welfare is influenced more by housing
conditions than by stocking density. Nature 342 – 344.
Dellmeier G.R., Friend T.H., Gbur E.E. 1985. Comparison of four methods of calf confinement.
II. Behavior. Journal of Animal Science 60: 1102 – 1109.
Dewey C.E., Friendship R.M., Wilson M.R.1993. Clinical and postmortem examination of sows
culled for lameness. The Canadian Veterinary Journal 34: 555 – 556.
Dudink S., Simonse H., Marks I., de Jonge F.H., Spruijt B.M. 2006. Announcing the arrival of
enrichment increases play behaviour and reduces weaning-stress-induced behaviours of
piglets directly after weaning. Applied Animal Behaviour Science 101: 86 – 101.
Duncan I.J.H. 1993. Welfare is to do with what animals feel. Journal of Agricultural and
Environmental Ethics Suppl. 6: 8 – 14.
Elbers A.R.W., Miltenburg J.D., de Lange D., Crauwels A.P.P., Barkema, H.W., Schukken Y.H.
1998. Risk factors for clinical mastitis in a random sample of dairy herds from the
southern part of The Netherlands. Journal of Dairy Science 81: 420 – 426.
Ernst K., Puppe B., Schön P.C., Manteuffel G. 2005. A complex automatic feeding system for
pigs aimed to induce successful behavioural coping by cognitive adaptation. Applied
Animal Behaviour Science 91: 205 – 218.
Eurobarometer. 2007. Attitudes of consumers towards the welfare of consumed animals.
Special Eurobarometer 229 (2), European Commission.
FAO. 2011. World Livestock 2011, Livestock in Food Security: Feeding the future. Food and
Agriculture Organization of the United Nations. http://www.fao.org/
FAO. 2009. Food and Agriculture Organization of the United Nations. The state of food
and agriculture: Livestock in the balance. Rome, ISSN 0081-4539.
FAO. 2006. Food and Agriculture Organization of the United Nations. Livestock Report
2006. Rome, ISBN 92-5-105421-5
FAWC. 2011. Final report. Farm Animal Welfare Council, London, UK.
FAWC. 2009. Farm animal welfare in Great Britain: past, present an future. Farm Animal Welfare
Council, London, UK.
FAWC. 1992. Report on the Welfare of Broiler Chickens. Farm Animal Welfare Council, Surbiton,
Surrey.
Feldman Barrett L., Russell J.A. 1998. Independence and bipolarity in the structire of current
affect. Journal of Personality and Social Psychology 74: 967 – 984.
Fisher A., Matthews L. 2001. The social behavior of sheep. In: Keeling L.J., Gonyou H.W. (eds):
Social behavior in farm animals. Wallingford, UK: CAB International. p. 211 – 245.
Fletcher D.L. 1999. Recent advances in poultry slaughter technology. Poultry Science 78: 277 –
281.
Flower F.C., Weary D.M. 2003. Effects of early separation on the dairy cow and calf. Animal
Welfare 12: 339 – 348.
53
Forsberg E.M. 2011. Inspiring respect for animals through the law? Current development in the
Norwegian animal welfare legislation. Journal of Agricultural and Environmental Ethics
24: 351 -366.
Fraser D., Broom D.M. 1990. Farm animal behaviour and welfare. Saunders, New York.
Fraser D., Broom D.M. 2007. Domestic animal behaviour and welfare. Cambridge University
Press, Cambridge, UK.
Fraser D., Duncan I.J.H. 1998. ‘Pleasures’, ‘pains’ and animal welfare: toward a natural history
of affect. Animal Welfare 7: 383 – 396.
Fraser D., Weary D.M. 2003. Quality of life for farm animals: linking science, ethics, and
animal welfare. In: Benson G.J. & Rollin B.E. The Well-being of Farm Animals: Challenges
and Solutions. Blackwell Publishing, Oxford, UK.
Fregonesi J.A., Leaver J.D. 2002. Influence of space allowance and milk yield level on behaviour,
performance and health of dairy cows housed in strawyard and cubicle systems.
Livestock Production Science 78: 245–257
Fregonesi J.A. Leaver J.D. 2001. Behaviour, performance and health indicators of welfare for
dairy cows housed in strawyard or cubicle systems. Livestock Production Science 68: 205
– 216.
Fregonesi J.A., Tucker C.B., Weary D.M. 2007. Overstocking reduces lying time in dairy cows.
Journal of Dairy Science 90: 3349 – 3354.
Friend T. 1989. Recognizing Behavioral needs. Applied Animal Behaviour Science 22: 151 – 158.
Galindo F., Broom D.M., Jackson P.G.G. 2000. A note on possible link between behaviour and
the occurrence of lameness in dairy cows. Applied Animal Behaviour Science 67 : 335 –
341.
Gentry J.G, Johnson A.K., McGlone J.J. 2008. In: Faucitano L., Schaefer A.L. (eds): Welfare of
pigs: from birth to slaughter. Wageningen Academic Pub.
Gilchrist M.J., Greko C., Wallinga D.B., Beran G.W., Riley D.G., Thorne P.S. 2007. The
potential role of concentrated animal feeding operations in infectious disease epidemics
and antibiotic resistance. Environmental Health Perspectives 115(2): 313 – 316.
Gonyou H.W., Chapple R.P. and Frank G.R. 1992. Productivity, time budgets and social aspects
of eating in pigs penned in groups of five or individually. Applied Animal Behaviour
Science 34: 291 – 301.
Grandin T. 1997. Assessment of stress during handling and transport. Journal of Animal Science
75: 249 – 257.
Hammell K.L., Metz J.H.M., Mekking P. 1988. Sucking Behaviour of dairy calves fed milk ad
libitum by bucket or teat. Applied Animal Behaviour Science 20: 275 – 285.
Hansen S.K., von Borell E. 1999. Behavior and heart rate variability as indicators for short and
long term changes in the mental state of pigs that received regular grooming simulation.
Aktuelle Arbeiten zur artgemäβen Tierhaltung. Darmstadt: KTB, p. 81 – 89.
Hargreaves A.L., Hutson G.D. 1990. The effect of gentling on heart rate, flight distance and
aversion of sheep to a handling procedure. Applied Animal Behaviour Science 26: 243 –
252.
Hartung J. 2003. Effects of transport on health of farm animals. Veterinary Research
Communications 27: 525 – 527.
Hawkins P. 2010. Chapter 3: The welfare implications of housing captive wild and domesticated
birds. In: Duncan I.J.H., Hawkins P. (eds): Welfare of domestic fowl and other captive birds.
Animal Welfare Volume 9, Springer.
Hemsworth P.H., Barnett J.L., Beveridge L., Matthews L.R. 1995. The welfare of extensively
managed dairy cattle: a review. Applied Animal Behaviour Science 42: 16 1 – 182.
Hemsworth P.H., Barnett J.L., Coleman G.J. and Hansen C. 1989. A study of the relationships
between the attitudinal and behavioural profiles of stockpersons and the level of fear of
humans and reproductive performance of commercial pigs. Applied Animal Behaviour
Science 23: 301 – 314.
54
Hemsworth P.H., Coleman G.J. 2011. Human-Livestock interactions: the stockperson and the
productivity and welfare of intensively farmed animals, 2nd ed. CAB International,
London, UK.
Hewson C.J. 2003. What is animal welfare? Common definitions and their practical
consequences. Canadian Veterinary Journal 44: 496 – 499.
Hewson C.J. 2001. Focus on animal welfare. Canadian Veterinary Journal 44: 335 – 336.
Hocking P.M., Maxwell M.H., Mitchell M.A. 1993. Welfare assessment of broiler breeder and
layer females subjected to food restriction and limited access to water during rearing.
British Poultry Science 34: 443 – 458.
Hogan J., Smith K.L. 2003. Coliform mastitis. Veterinary Research 34: 507 – 519.
Horgan R. 2006. EU animal welfare legislation: current position and future perspectives.
European Commission, Bruxelles.
Huber-Eicher B., Wechsler B. 1998. The effect of quality and availability of foraging materials
on feather pecking in laying hen chicks. Animal Behaviour 55: 861 – 873.
Huzzey J.M., de Vries T.J., Valois P., von Keyserlingk M.A.G. 2006. Stocking density and feed
barrier design affect the feeding and social behavior of dairy cattle. Journal of Dairy
Science 89: 126 – 133.
Jendral M. 2005. Alternative layer hen housing systems in Europe. Report prepared for Alberta
Egg Producers and Alberta Farm Animal Care Association. World Poultry Congress,
Germany.
Jensen M.B., Kyhn R. 2000. Play behaviour in group-housed dairy calves, the effect of space
allowance. Applied Animal Behaviour Science 67: 35 – 46.
Jensen K.H., Pedersen B.K., Pedersen L.J., Jorgensen E. 2009. Well-being in pregnant sows:
confinement versus group housing with electronic sow feeding. Acta Agriculturae
Scandinavica 45: 266 – 275.
Jensen M.B., Vestergaard K.S., Krohn C.C. 1998. Play behaviour in dairy calves kept in pens:
the effect of social contact and space allowance. Applied Animal Behaviour Science 56: 97
– 108.
Kadzere C.T., Murphy M.R., Silanikove N., Maltz E. 2002. Heat stress in lactating dairy
cows: a review. Livestock Production Science 77: 59 – 91.
Keppler C., Fölsch D.W. 2000. Locomotive behaviour of hens and cocks (Gallus gallus f.
domesticus); implications for housing systems. Archiv für Tierschutz 43: 184 – 188.
Kerr S.G.C., Wood-Gush D.G.M. 1987. A comparison of the early behaviour of intensively and
extensively reared calves. Animal Production 45: 181 – 190.
Kijlstra A., Eijck I.A.J.M. 2006. Animal health in organic livestock production systems: a review.
NJAS – Wageningen Journal of Life Sciences 54: 77 – 94.
Knowles T.G., Broom D.M. 1990. Limb bone strength and movement in laying hens from
different housing systems. Veterinary Record 126: 354 – 356.
Knutson B., Burgdorf J., Panksepp J. 2002. Ultrasonic vocalizations as indices of affective
states in rats. Psychological Bulletin 128: 961 – 977.
Korte S.M., Olivier B., Koolhaas J.M. 2007. A new animal welfare concept based on allostasis.
Physiology & Behavior 92: 422 – 428.
Kroneman A., Vellenga L., van der Wilt F.J., Vermeer H.M. 1993. Review of health problems in
group‐housed sows, with special emphasis on lameness. Veterinary Quarterly 15: 26 –
29.
Lensink B.J., Fernandez X., Boivin X., Pradel P., Le Neindre P., Veissier I. 2000. The impact of
gentle contacts on ease of handling, welfare, and growth of calves and on quality of veal
meat. Journal of Animal Science 78: 1219 – 1226.
Manteuffel G., Puppe B., Schön P.C. 2004. Vocalization of farm animals as a measure of
welfare. Applied Animal Behaviour Science 88: 163 – 182.
Marchant-Forde J.N. 2009. The welfare of pigs. Animal Welfare, Volume 7, Springer.
Marchant J.N., Rudd A.R., Mendl M.T., Broom D.M., Meredith M.J., Corning S., Simmins P.H.
2000. Timing and causes of piglet mortality in alternative and conventional farrowing
systems. Veterinary Record 147: 209 – 214.
55
Mason G.J. 1991. Stereotypies: a critical review. Animal Behaviour 41: 1015 – 1037.
McFarlane I. S. 1972. Bovine behavior patterns. Livestock Breeding Journal 6.
Meluzzi A., Sirri F. 2009. Welfare of broiler chickens. Italian Journal of Animal Science 8: 161 –
173.
Mench J.A. 2002. Broiler breeders: feed restriction and welfare. Worlds Poultry Science Journal
58: 23 – 29.
Mench J.A., van Tienhoven A. 1986. Farm animal welfare: behavioral and physiological studies
are providing a basis for the development of innovative housing. American Scientist 74:
598 – 603.
Moberg G.P. 1985. Biological response to stress: key to assessment of animal well-being?
Symposium on animal stress, Univ. of California, Moberg, G.P. (ed.).- Bethesda, Md. (USA):
American Physiological Society, 1985, p27 – 49.
Moelk M. 1944. Vocalizing in the house-cat: a phonetic and functional study. The American
Journal of Psychology 57: 184 – 205.
Moura D.J., Nääs I.A., Pereira D.F., Silva R.B.T.R., Camargo G.A. 2006. Animal welfare concepts
and strategy for poultry production: a review. Brazilian Journal of Poultry Science 8: 13 7
– 148.
NASS. 2005. U.S. broiler and egg production cycles. National Agricultural Statistics Service,
agricultural statistics board, U.S. department of agriculture. Washington D.C., USA.
Available at: http://usda01.library.cornell.edu/usda/current/usbepc/usbepc-09-162005.pdf
Newberry R.C., Estevez I., Keeling L.J. 2001. Group size and perching behaviour in young
domestic fowl. Applied Animal Behaviour Science 73: 117 – 129.
Newberry R.C., Wood-Gush D.G.M., Hall J.W. 1988. Playful behaviour of piglets. Behavioural
Processes 17: 205 – 216.
Nicol C.J. 1987. Behavioural responses of laying hens following a period of spatial restriction.
Animal Behaviour 35: 1709 – 1719.
O’Connell N.E. 2009. Housing the fattening pig. In: Marchant-Forde J.N. (ed), The welfare of pigs.
Chapter 6. Animal Welfare, Volume 7, Springer.
Ohl F., Hellebrekers L.J. 2009. ‘Dierenwelzijn’ – De diergeneeskundige positie (‘Animal welfare
– the veterinary position’, in Dutch). Tijdschrift voor Diergeneeskunde 134: 754 – 755.
Ohl F., van der Staay F.J. 2011. Animal welfare: At the interface between science and society.
The Veterinary Journal 192: 13 – 19.
OIE. 2009. Animal welfare and broiler chicken production. Terrestrial animal health standards
commission report. World Organisation for Animal Health. http://www.oie.int/
Overall K.L., Rodan I., Beaver B.V., Carney H., Crowell-Davis S., et al. 2005. Feline behavior
guidelines from the American Association of Feline Practitioners. Journal of the American
Veterinary Medical Association 227: 70 – 84.
Pankey J.W. 1989. Hygiene at milking time in the prevention of bovine mastitis. British
Veterinary Journal 145: 401 – 409.
Pitts A.D., Weary D.M., Pajor E.A., Fraser D. 2000. Mixing at young ages reduces fighting in
unacquainted domestic pigs. Applied Animal Behaviour Science 68: 191 –197.
PostNote. 2011. Livestock disease. The Parliamentary Office of Science and Technology,
London.
Potter M.J., Broom D.M. 1987. The behaviour and welfare of cows in relation to cubicle house
design. In: Wierenga H.K., Peterse D.J. (eds.): Cattle Housing Systems, Lameness and
Behaviour. Martinus Nijhoff, Dordrecht, pp. 129–147.
Pressman S.D., Cohen S. 2005. Does positive affect influence health? Psychological Bulletin 131:
925 – 971.
Raj M. 1998. Welfare during stunning and slaughter of poultry. Poultry Science 77: 1815 – 1819.
Rauw W.M., Kanis E., Noordhuizen-Stassen E.N., Grommers F.J. 1998. Undesirable side
effects of selection for high production efficiency in farm animals: a review. Livestock
Production Science 56: 15 – 33.
56
Reinhardt V., Reinhardt A. 1981. Cohesive relationships in a cattle herd (Bos indicus). Behavior
77: 121 – 151.
Roman-Ponce H., Thatcher W.W., Buffington D.E., Wilcox C.J., van Horn H.H. 1977.
Physiological and production responses of dairy cattle to a shade structure in a
subtropical environment. Journal of Dairy Science 3: 424 – 430.
Rushen J. 1984. Stereotyped behaviour, adjunctive drinking and the feeding periods of
tethered sows. Animal Behaviour 32: 1059 – 1067.
Rushen J., A.M.B. de Passillé. 1992. The scientific assessment of the impact of housing on
animal welfare: A critical review. Canadian Journal of Animal Science 72: 721 – 743.
Rushen J., A.M.B. de Passillé, Munksgaard L. 1999. Fear of people by cows and effects on milk
yield, behavior, and heart rate at milking. Journal of Dairy Science 82: 720 – 727.
Rutherford K.M.D. 2002. Assessing pain in animals. Animal Welfare 11: 31 – 53.
Salomons A.R., Arndt S.S., Ohl F. 2009. Anxiety in relation to animal environment and welfare.
Scandinavian Journal of Laboratory Animal Science 36: 37 – 45.
Sanford J., Ewbank R., Molony V., Tavernor W.D., Uvarov O. 1986. Guidelines for the
recognition and assessment of pain in animals. Veterinary Record 118: 334 - 338.
Sato S., Hatae K., Tarumizu K. 1993. The influence of social factors on allogrooming in cows.
Applied Animal Behaviour Science 38: 235 – 244.
Sato S., Sako S., Maeda A. 1991. Social licking patterns in cattle (Bos taurus): Influence
of environmental and social factors. Applied Animal Behaviour Science 32: 3 – 12.
Sato S., Tarumizu K. 1993. Heart rates before, during and after allo-grooming in cattle (Bos
taurus). Journal of Ethology 11: 149 – 150.
Shae M.M., Mench J.A., Thomas O.P. 1990. The effect of dietary tryptophan on aggressive
behavior in developing broiler breeder males. Poultry Science 69: 1664 – 1669.
Sherwin C.M. 2010. Chapter 10: The welfare and ethical assessment of housing for egg
production. In: Duncan I.J.H., Hawkins P. (eds): Welfare of domestic fowl and other captive
birds. Animal Welfare Volume 9, Springer.
Shields S.J., Garner J.P., Mench J.A. 2005. Effect of sand and wood-shavings bedding on the
behavior of broiler chickens. Poultry Science 84: 1816 – 1824.
Shuster D.E., Lee E.K., Kehrli M.E. Jr. 1996. Bacterial growth, inflammatory cytokine
production, and neutrophil recruitment during coliform mastitis in cows within
ten days after calving, compared with cows at midlactation. American Journal of
Veterinary Research 57: 1569 – 1575.
Scholz B., Urselmans S., Kjaer J.B., Schrader L. 2010. Food, wood, or plastic as substrates for
dustbathing and foraging in laying hens: A preference test. Poultry Science 89: 1584 –
1589.
Schouten W.G., Wiegant V.M. 1997. Individual responses to acute and chronic stress in pigs.
Acta Physiologica Scandinavica 640: 88 – 91.
Spinka M., Newberry R.C., Bekoff M. 2001. Mammalian play: training for the unexpected. The
Quarterly Review of Biology 76 141 – 168.
Stafleu F.R., Grommers F.J., Vorstenbosch J. 1996. Animal welfare: evolution and erosion of a
moral concept. Animal Welfare 5: 225 – 234.
Stolba A., Wood-Gush D.G.M. 1989. The behaviour of pigs in a semi-natural environment.
Animal Production 48 419 – 425.
Studnitz M., Jensen M.B., Pedersen L.J. 2007. Why do pigs root and in what will they root? A
review on the exploratory behaviour of pigs in relation to environmental enrichment.
Applied Animal Behaviour Science 107: 183 – 197.
Stull C., Reynolds J. 2008. Calf welfare. Veterinary Clinics of North America: Food Animal
Practice 24: 191 – 203.
SVC. 1997. The welfare of intensively kept pigs. Scientific Veterinary Committee. Available from:
http://europa.eu.int/comm/food/fs/sc/oldcomm4/out17_en.pdf.
Swanson J.C. 1995. Farm animal well-being and intensive production systems. Journal of Animal
Science 73: 2744 – 2751.
57
Tannenbaum J. 1991. Ethics and animal welfare: the inextricable connection. Journal of the
American Veterinary Medical Association 198: 1360 – 1376.
Teagasc – the Agriculture and Food Development Authority. 2012. Towards January
2013. Updates, implications and options for group housing pregnant sows. Pig
Development Department, Moorepark, Ireland.
Thompson K.V. 1998. Self-assessment in juvenile play. In: Bekoff M., Byers J.A. (eds): Animal
play: evolutionary, comparative and ecological perspectives. Cambridge University Press.
Thornton P.D., Waterman-Pearson A.E. 2002. Behavioural responses to castration in lambs.
Animal Welfare 11: 203 – 212.
Toghyani M., Gheisari A., Modaresi M., Tabeidian S.A., Toghyani M. 2010. Effect of different
litter material on performance and behavior of broiler chickens. Applied Animal
Behaviour Science 122: 48 – 52.
Troeger K. 2004. Overview of current and alternative slaughter practices. Biotechnologie,
Agronomie, Société et Environnement 8: 275 – 281.
Trunkfield H.R. , Broom D.M. 1990. The welfare of calves during handling and transport.
Applied Animal Behaviour Science 28: 135 – 152.
Tucker C.B. 2003. The effects of freestall surfaces and geometry on dairy cattle behavior. Master
Thesis, Faculty of Agricultural Sciences, University of British Columbia, Canada.
Tucker C.B., Rogers A.R., Schütz K.E. 2007. Effect of solar radiation on dairy cattle behaviour,
use of shade and body temperature in a pasture-based system. Applied Animal Behaviour
Science 109: 141 – 154.
Tucker C.B., Weary D.M. 2001. Stall design: enhancing cow comfort. Advances in Dairy
Technology 13: 155 – 167.
Turner S.P., Ewen M., Rooke J.A., Edwards S.A. 2000. The effect of space allowance on
performance, aggression and immune competence of growing pigs housed on straw
deeplitter at different group sizes. Livestock Production Science 66: 47 – 55.
Ucko J., Dumbleby G.W. 1969. The domestication and exploitation of plants and animals. The
garden city press limited, Hertfordshire, England.
UN population division. 2011. World Population Prospects: The 2010 Revision. New York:
United Nations.
Vanderschuren L.J.M.J., Niesink R.J.M., van Ree J.M. 1997. The neurobiology of social play
behavior in rats. Neuroscience & Biobehavioral Reviews 21: 309 – 326.
van de Weerd H.A., Day J.E.L. 2009. A review of environmental enrichment for pigs housed in
intensive housing systems. Applied Animal Behaviour Science 116: 1 – 20.
van Lier D.W., Bokma S. 1987. Short-term feather maintenance as a function of dust-bathing in
laying hens. Applied Animal Behaviour Science 18: 197 – 204.
van Ree J.M., Niesink R.J.M., van Wolfswinkel L., et al. 2000. Endogenous opioids and reward.
European Journal of Pharmacology 405: 89 – 101.
Veissier I., Capdeville J., Delval E. 2004. Cubicle housing systems for cattle: comfort of dairy
cows depends on cubicle adjustment. Joural of Animal Science 82: 3321 – 3337.
Vigne J-D. 2011. The origins of animal domestication and husbandry: A major change in the
history of humanity and the biosphere. Comptes Rendus Biologies 334: 171 – 181.
Warnick L.D., Janssen D., Guard C.L., Gröhn Y.T. 2001. The effect of lameness on milk
production in dairy cows. Journal of Dairy Science 84: 1988 – 1997.
Warriss P.D. 1998. The welfare of slaughter pigs during transport. Animal Welfare 7: 365 – 381.
Watts J.M., Stookey J.M. 2000. Vocal behaviour in cattle: the animal’s commentary on its
biological processes and welfare. Applied Animal Behaviour Science 67: 15 – 33.
Webster A.J.F. 2005. The assessment and implementation of animal welfare: theory into
practice. Revue Scientifique et Technique - Office international des épizooties 24: 723 –
734.
Webster A.J.F. 2001. Farm animal welfare: the five freedoms and the free market. The
Veterinary Journal 161: 229 – 237.
58
Webster A.J.F. 1994. Comfort and injury. In: Wathes C.M., Charles D.E. (eds): Livestock housing.
Wallingford, UK. CAB International, p 50 – 51.
Weeks C.A., Nicol C.J. 2006. Behavioural needs, priorities and preferences of laying hens.
World’s Poultry Science Journal 62 296 – 307.
Weeks C.A., Nicol C.J., Sherwin C.M., Kestin S.C. 1994. Comparison of the behaviour of broiler
chickens in indoor and free-range environments. Animal Welfare 3: 179 – 192.
Wegner R.M. 1990. Experience with the get-away cage system. World’s Poultry Science Journal
46: 41 – 47.
Weiss J. M. 1972. Psychological factors in stress and disease. Scientific American 226: 104 – 108.
WHO. 1946. World Health Organization, Preamble to the Constitution of the World Health
Organization as adopted by the International Health Conference, New York, 19–22 June.
Widowski T.M. 2010. Chapter 6: Introduction. In: Duncan I.J.H., Hawkins P. (eds): Welfare of
domestic fowl and other captive birds. Animal Welfare Volume 9, Springer.
Widowski T.M., Duncan I.J.H. 2000. Working for a dustbath: are hens increasing pleasure
rather than reducing suffering? Applied Animal Behaviour Science 68: 39 – 53.
Wieringa H.K., Hopster H. 1990. The significance of cubicles for the behaviour of dairy cows.
Applied Animal Behaviour Science 26: 309 – 337.
Wise J.K., Heathcott B.L., Shepherd A.J. 2003. Results of the 2002 AVMA survey of US petowning households regarding use of veterinary services and expenditures. Journal of the
American Veterinary Medical Association 222: 1524 – 1525.
Yeates J.W., Main D.C.J. 2008. Assessment of positive welfare: a review. The Veterinary Journal
175: 293 – 300.
Zimmermann M. 1986. Behavioural investigations of pain in animals. In: Duncan R.J.H. and
Molony V.: Assessing Pain in Farm Animals pp 16-27. Commission of the European
Communities: Luxembourg
59
5.1 Sources of images used
Front page:
http://buncombecounty4h.files.wordpress.com/2009/12/horse-cow-pig-chicken.gif
Section 2.4 Natural behaviour:
Chicken pecking: http://www.123rf.com/photo_492902_brown-chicken-pecking.html
Pig rooting: http://www.pigbrotheratmirrorbrook.co.uk/piglife.html
Cow grazing: http://www.molevalleyfarmers.com/mvf/info/farming/Establishing_a_New_Ley
Section 3.2 Cattle:
Cows in lying cubicles: http://www.animalcomfort.co.uk/
Cows eating hay: http://www.fbibuildings.com/dairy/
Calve in hutch: USDA Photo Center; http://ocw.tufts.edu/data/40/508880/508893_xlarge.jpg
Calve in crate: www.farmsanctuary.org
Section 3.3 Pigs:
Sow in farrowing crate:
http://www.bigdutchman.de/fileadmin/photos/schwein/haltung_stalleinrichtungen/Abferkelb
ucht_farrowing_crate_08.jpg
Fattening pigs:
http://www.bigdutchman.de/fileadmin/photos/schwein/haltung_fuetterung/Mastabteil_Fluess
igfuetterung_liquid_feeding_2.jpg
Section 3.4 Poultry:
Chickens perching: http://labanimals.awionline.org/pubs/cq02/Cq-chick.html
Chickens dustbathing: http://thedailydish.us/chicken-update/
Battery cage hens: http://www.foodsafetynews.com/2012/01/european-union-bans-batterycages-for-egg-laying-hens/
Hens in barn system: http://www.bartalthuizen.nl/blog/wp-content/uploads/2012/03/Vrijuitloopkippen-Jan-Meijer-13.jpg
Broiler chickens in barn: http://www.candhlivestock.com/images/chickens/
60