1
2.3 PRE-SLAUGHTER TREATMENT
PRESLAUGHTER HANDLING OF ANIMALS AND ITS EFFECT ON
MEAT QUALITY
General Aspects
The chain of events between the producer and consumer is of
primary importance for the quality of slaughter animals and meat
including pork.
Even though all details have not been fully clarified, it is known that
some points in the chain are much more important than others:
FARM→TRANSPORT→LAIRAGE→SLAUGHTER
The different aspects of pre-slaughter treatment cannot be
considered separately, they are a whole chain of interactive
events.
Conditions vary between countries with regard to climate, transport,
the system of collection, the length of transport, etc. that only general
rules can be given.
Health/Stress/Contamination
STRESS
STRESS
The animals are subjected a wide variety of stressors, many of which
may have adverse effects with subsequent deleterious changes in
the carcass, even death may occur:
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Process of loading on the farm
Journey to the abattoir or the market
Period of holding in the market
Off-loading (might occur more than once a day)
The detention on the abattoir lairage
Subsequent handling up to the point slaughter
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In addition to the physical trauma (bruising) other stresses (stressors)
are:
 Sound, light, heat, humidity, cold, wind, fear, poor
feeding/watering, starving, fatigue, socialisation/grouping, fighting,
exhaustion all these may reflect of handling problems.
GENOTYPE (THROUGH EXAMPLE OF PSE/DFD)
Some pigs are genetically predisposed to the development of PSEmeat but the mode of inheritance seems to be rather complicated.
A high proportion of meat quality problems are related to the
phenomenon of stress susceptibility in pigs.
Stress susceptible pigs are prone to the “sudden death” syndrome
and can die just being moved from one pen to another on the farm or
during transport to the abattoir.
Sudden deaths in fattening pigs, often having a high degree of
muscling, have been shown to be associated with malignant
hyperthermia, a rapid increase in lactate, muscle rigidity and
development of PSE meat (Halothane sensitivity: a mixture of 3-5%
halothane in oxygen for 3-5 min).
Stress susceptible pigs are relatively insensitive to changes in the
preslaughter environment, in most cases (under any condition)
developing either PSE meat or DFD meat (or both) depending on the
treatment.
Stress-resistant pigs, on the other hand, will be more responsive to
changes in preslaughter treatment, developing PSE meat only after
severe short-term stress or DFD meat after prolonged stress.
Feeding pigs on the day of slaughter and giving them a short
transport and lairage will result in higher energy reserves at
slaughter, a higher PSE frequency and a lower DFD frequency than
pigs without feeding on the day of slaughter and giving them a longer
transport and lairage.
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Fighting among pigs will always lower the PSE frequency and
increase the DFD frequency.
Very prolonged transport and/or lairage, where some of the pigs can
relax and recoup energy losses, will lead to an increase in both PSE
and DFD meat in stress-susceptible pigs.
In a test, pigs were transported in a well-equipped vehicle with
mechanical ventilation, partitions, and a non-slip flooring. The PSE
frequency fell to a quarter just by increasing transport time from 15
min to 3 hours. The DFD incidence increased correspondingly.
With the same transport conditions and 1 hour transport, the PSE
incidence more than halved by increasing holding time in lairage from
0 up to 4 hours. DFD frequency increased with longer lairage time.
Results indicate that any increase (exposure time/frequency) in
stress in animals that have already been subjected to many
unfamiliar situations will only cause a greater degree of exhaustion
and hence a higher DFD frequency and lower PSE frequency.
WHAT TO DO?
 Fighting between pigs should be minimised at all points of the
chain
 Improvement of handling must be accompanied by genetic
improvement via breeding programmes, thereby keeping the number
of susceptible pigs as low as possible.
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TYPES, MECHANISMS OF STRESS
Animal is said to be in a state of stress if it is required to make
abnormal or extreme adjustments in its physiology or behaviour in
order to cope with adverse aspects of its environment and
management.
A husbandry system is said to be stressful if it makes abnormal
demands on the animal.
Stress is non-specific response of an animal attempting to resist or
adapt to maintain homeostasis.
There are two main types of reactions of the animal to stress:
 The alarm or emergency reaction
 The general adaptation syndrome
These are termed together: Fight or flight syndrome.
The alarm reaction is for sudden adverse stimuli and takes place
immediately. It is accompanied with an increased activity of
sympathetic nervous system (heart, involuntary muscles, secreting
glands) resulting in catecholamine release and elevated heart rate
and increased force of contraction and blood pressure,
vasoconstriction, bronchodilatation, cessation of digestion and
mobilisation liver glycogen and increase of blood sugar (Glucagon
also mobilises blood glucose from liver glycogen).
Stress factors demand increased oxygen intake and increased blood
flow to and from lungs loading further the ab ovo (basically) weak
heart of the intensively fattened animals.
Death will ensure if the heart is unequal to stress (post mortem
findings: acute cardiac dilatation, acute pulmonary hyperaemia, lungs
are heavy, firmer, finger impression is kept, frothy water is coming
from the cut surface, acute, passive hyperaemia if liver and spleen
might also been observed. Left ventricle is not conical but oval, apex
is rounded, papillary muscles and trabeculae are flat, pericardial fluid
is increased, there is diffuse, severe skeletal muscle degeneration
and inferior meat quality). (Concerning that the sympathetic system is
also involved in mechanism of stress, dantrolene sodium,
tranquillisers have beneficial effects).
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The general adaptation syndrome is long-lasting in nature. Also, by
the released ACTH the metabolism is directed on the long run
(cortisol, cortisone).
There is a decrease in carbohydrate metabolism and an increase in
protein metabolism. Amino acids are converted into glycogen in the
liver. Fat is mobilized from depots and is metabolized in the liver
producing ketone bodies.
The overall result is a high blood glucose level and ketosis.
Other changes: hypertrophy of the adrenal gland with reduction its
ascorbic acid and cholesterol stores, eosinopenia, lymphopenia,
polynucleosis (increase in PMN) and increased susceptibility to
disease. The syndrome leads to reduced growth rate in young
animals and loss of weight in adult animals.
Stress proteins.
Stress factors demand increased oxygen intake and increased blood
flow to and from lungs loading further the ab ovo (basically) weak
heart of the intensively fattened animals.
Death will ensure if the heart is unequal to stress (post mortem
findings: acute cardiac dilatation, acute pulmonary hyperaemia, lungs
are heavy, firmer, finger impression is kept, frothy water is coming
from the cut surface, acute, passive hyperaemia if liver and spleen
might also been observed. Left ventricle is not conical but oval, apex
is rounded, papillary muscles and trabeculae are flat, pericardial fluid
is increased, there is diffuse, severe skeletal muscle degeneration
and inferior meat quality).
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FARM
Pre-slaughter treatment in wide sense commences already at the
producing plant (farm). While faecal contamination of hides, fleeces
and the skin of animals can arise during transportation and even in
the slaughterhouse lairage, the most important source, however is
the farm.
Loss of income due to soiling of hides is in the environ of 20 million
pounds a year, but the total figure for all species along with the
contamination of carcasses and the transfer of pathogenic organisms
to meat is incalculable. To reduce these losses, the followings should
keep in mind.
 The use of chemical and pharmaceutical preparations on the farm
 The promotion of high health standards in livestock and their
general care during transportation, at auction markets and in
slaughterhouse lairages.
 Ante-mortem examination to eliminate unfit animals and to make
provision for special post-mortem examinations (feed-back)
 Post-mortem examination of the carcass and offal immediately
after slaughter, including laboratory testing where necessary (feedback)
 Removal of material unfit for human consumption and its efficient
destruction at processing plants located outside the meat plant
 High standards of hygiene at all stages from the farm to the
slaughterhouse, meat processing factory (meat plant), cold store,
restaurant kitchen and the consumers’ home.
The production of carcasses of high hygienic standards demands
sound husbandry methods that pay close attention to animal health
as well as cleanness in the final stages of finishing.
The following points should be given due attention by farmers
producing stock for slaughter:
 Housing structure and layout
 Housing density
 Grooming (flanks, bellies should be clipped before the stock is
housed)
 Management (to ensure that slaughter animals do not become
dirty)
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 Internal parasitism
 If cattle, sheep are feeding on root crops in fields, they should be
transferred to clean grazing or housing for a period before being
dispatched for slaughter
 Arrangements should be made for wet animals to dry out before
being loaded for the meat plant
 Transport and abattoir lairages- the same clean conditions must be
applied during transportation and the wait for slaughter
TRANSPORTATION OF LIVESTOCK
Purpose: To keep animals free from contamination during the
subsequent movement to the point of slaughter.
They should be kept free from injury, stress, loss of weight and
disease during the journey.
The humanitarian aspects of the transportation of animals are
intimately linked with the economic ones (especially in case of young
stock and casualty animals).
For all these reasons, long journeys should be avoided.
 Light meal only before journey. For cattle, horses and sheep food
and water need to be available before and during transportation
and in transit. Withdrawal may result in dehydration and ketosis.
For poultry and pigs, food should be withheld approximately 6
and 12 hours before transport, respectively, while water remains
available.
 Wood shavings bedding
 Loading densities must be considered
 Any injured or severely stressed pig should be separated from the
rest and moved to special pens or for emergency slaughtering.
From veterinary aspects transportation should satisfy the following
demands:
 Prevention of the spread of disease
 Observance of the necessary standard of hygiene
 Avoidance of unnecessary suffering during transport
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During transport animals do not suffer from:
 Exposure to weather
 Inadequate ventilation
 Inadequate facilities of any kind
 Fall out the vehicle
 Other causes
Where floors are not anti-slip design, sand or any other suitable
material may be used.
Partitions in vehicles for the separation of animals must be enough
high (cattle: 130 cm, pig and sheep: 75 cm).
In multitier vehicles sufficient distance between each floor and roof
must be left to enable animals to stand upright and allow proper
access and circulation of air.
A knowledge of animal behaviour is fundamental for proper animal
transportation and further handling. The minimizing of stress along
period of transportation and rest before slaughter have beneficial
effect on the appearance, quality and marketability of the carcass.
Animals can be transported only by lorries and trucks suitably
equipped for this purpose:
 Having non-slippery and leak-proof floors
 Supplied with proper restrains or fences
 Roof or blanket for shielding if necessary
 Adequate aeration
 Vehicle with lift to load/unload animals is preferred
 If ramps are used those are non-slippery, equipped by side
barriers to prevent animals from falling down the ramp (the maximum
acceptable slope is 35 degrees (EEC suggestion is 20 degrees)
If transportation lasts longer than 30 min, animals should be
transported in covered vehicles. During summer it is recommended
to transport animals early in the morning or during the night to avoid
overheating.
Animals must be watered every 6 hour of transportation and beyond
12 hours they must be fed, too and the place must be littered.
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The adequate space on the floor (EC, 1992):

Cattle: 0.4-2.0 m2
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Pigs: 0.15-0.51 m2
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Heavy pigs: 0.7 m2

Sheep: 0.14-0.34 m2
These values may vary according to local legislative.
If animals are transported in container, cages or basket, those must
be large enough to allow animals to stand. Sufficient aeration must
be provided. These holders of animals are not allowed to overturn.
Horseshoes of solipeds must be removed.
Animals tend to be frightened and nervous thus, additional
excitement usually does not necessarily increase the speed of
loading/unloading movement.
Bruising in various degrees, injury, fractures or death of animals may
be the result of the behaviour of the personnel present at
loading/unloading, transport.
To move the stock as fast as possible, keeping them calm and at
ease, it is recommended:
 Move animals in group (they feel safer and move faster in alleys
wide enough for several animals. However, too big groups may be
difficult to handle)
 Do not be in hurry. It will not increase the speed of the stock
unless it is heavily stressed and/bruised
 Do not use too much force and noise. Lorry drivers, farm and
lairage personnel must be properly trained and the possible use of
various tools of forcing should be restricted.
The personnel responsible for the road transport of livestock have a
duty to ensure carefulness, avoiding sudden stops and starts, fast
cornering and unnecessary delays.
Animals must be protected from injury and unnecessary suffering
while being loaded and unloaded and during transport (protection
from inadequate fittings, influence of weather and poor ventilation).
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The transport of unfit animals and those likely to give birth during the
journey is prohibited.
Floors and ramps must be fitted with suitable battens to prevent
animals from slipping
Tying points must be supplied to secure animals where necessary.
Certain animals must not be carried in the same undivided vehicle,
for example:
 The transportation of different sexes or species of animals is
not allowed unless the vehicle is divided by a solid fence.
 Cow with suckling calf or calves
 Sow and piglets
 Horses and swine shall not be carried together in the same
vehicle, divided or undivided.
 Bull over 10 months of age must be secured by the head and
neck.
Partitions in vehicles for the separation of animals must be at least
1.27 m high in the case of cattle and horses, and 76 cm in all other
cases.
Carcasses must not be carried in vehicles in which live animal is
being carried. Animal died during the journey must be disposed
promptly at the nearest appropriate place.
Cleansing and disinfecting after unloading.
Loading and unloading must be carried out not cause injury or
unnecessary suffering and using vehicle rumps.
It is essential that during transportation animals do not suffer from
exposure to weather, inadequate ventilation or facilities of any kind
allowing the animals fall out the vehicle.
Attendant responsible for care of animals should accompany the
vehicle (driver or the guard of the train is also appropriate).
There must be sufficient distance between each floor and the roof in
multi-tier vehicle (1.98 m for horse).
Overcrowding of which would result in injury and unnecessary
suffering is forbidden.
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Adequate and suitable food and water must be offered to the animals
to eat in every 12 hour during the journey unless journey is
completed within 15 hours and the animals are fed immediately after
arrival.
Regulations, in general, are properly directed towards the prevention
of injury, disease and unnecessary suffering.
These regulations require the close co-operation of stock owners,
drivers, attendants and inspectors.
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BRUISING
The presence of bruising is apparent to the eye.
At slaughter, a bruise may be dated approximately by the following
appearances:
 0-10 hours old = Red and haemorrhagic
 About 24 hours old = Dark coloured
 24-38 hours = Watery consistency
 3+ days = Rusty, orange colour (bilirubin) and soapy to touch.
 A more specific method to dating is based on the formation of
bilirubin from haemoglobin in the area of bruise.
TEST
A sample of bruised meat is soaked in Fouché’s reagent
(trichloracetic acid and ferric chloride),
Bruises up to 50 hours old give no reaction
60-70 hours old the solution light blue
4-5 days old give a dark green reaction
The bilirubin test has shown 90 per cent of poultry bruises to be
inflicted 0-13 hours before slaughter.
The age of bruise can also be estimated by measuring the electrical
conductivity of the tissue, which increases up to a maximum at 40
hours.
Senseless, rough handling, abusive use of whips, electric goads are
responsible for the majority of injuries, causing just over 50% of all
the damage to carcasses. Falling down the ramp causes fractures
and sustained injuries.
Give animal time to move!
Approximately half the bruising in horned cattle is due to the
presence of horns. The incidence of mastitis is also higher in horned
stocks. Dehorning reduces the incidence by 50 per cent. The
presence of horns also makes for difficulties in subsequent carcass
dressing.
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TEMPERAMENT
The temperament of cattle obviously has an influence on the
incidence of bruising (breeds, individuals). Overcrowding
undoubtedly increases aggressiveness. Among the food animals, fat
pigs are the most likely to become deleteriously affected during
transport as their heat eliminating powers are very limited.
Bruising and bite marks on the surface of pigs cause depreciation in
market value. Most bruises occur during transport and a minor
proportion during loading and de- loading.
Pigs from different farms loaded on the same lorry are quite on the
lorry is in motion but start fighting as the lorry stops.
Reducing the stopping periods by 50 % reduces the incidence of bite
marks by 25%.
Premixing of socially unfamiliar groups of pigs in a holding pen for a
couple of days prior to transport also considerably reduces injuries
from fighting.
Bruising can be produced in animal both before and after stunning
until blood pressure falls to zero by bleeding.
The greater the distance and greater the number of stops, the higher
the incidence of bruising.
Probably the greatest cause of bruising and death of cattle during
transport is the moving of animals on the floor that is not provided
with metal grid.
HANDLING
The actual handling of livestock should always be carried out gently a
quietly.
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BREED
Some breeds of cattle (Braham and Afrikander) are notoriously
excitable.
In pigs certain breeds are susceptible to effects of stress (Pietrain,
Poland china).
INCENTIVES
In Canada, there is a tax on cattle with horns.
TRANSPORT MORTALITY
Sheep and pigs are frequently found dead as a result of suffocation
during transport (Mortality rate in West Europe was 0.15-1%).
Recently, the incidence of death of pigs has been increased:
 Living under fundamentally unnatural conditions
 Selective breeding for earlier maturity has increased
aggressiveness and sensitivity to stress-factors.
Risk factors during transportation:
 Feeding (heavy meal) before journey increase mortality
 Adequate ventilation to avoid suffocation and death and reduce
aggressiveness when temperatures and humidity are high.
 In summer, pigs should transported in the early morning
 On short journey, pig mortality is low but it might be 0.1% in
journeys of 100 km and 0.3-0.5% in journeys of 500 km (and the
quality of journey is also important).
If the olfactory background for aggression is proved, it would logical
to accustom strange pigs to each other a few days before embarking
to journey.
The use of tranquillizers is prohibited however it is suggested also to
offset weight loss (cattle, pigs).
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Careless injection can cause loss of meat due to severe tissue
reactions (gelatinous infiltration, haemorrhage, necrotic muscle. Loss
up to 2.2 kg was recorded).
EFFECT OF SOUND
Excessive and strident noise is very stressful for livestocks:
 Human voices
 Whips
 Noisy machinery
 Thunder
 Barking dogs
 Compressed air brakes of vehicles
 Alarm bells
 Noise of equipment (especially around the stunning area)
Cattle are more sensitive to higher frequencies of 8000 Hz (human:
1000-3000 Hz).
EFFECT OF HEAT AND COLD
Extremes of temperature, especially heat are dangerous (over 26.5
C (pigs) and humidity (over 20-25 %, relative)
In USA, livestock weather safety index chart indicates that in relation
to current temperature and relative humidity how safe stock transport
would be
LOSS OF WEIGHT DURING TRANSPORT
All animals transported to slaughter will suffer some loss of liveweight
during the journey. The loss is mainly of water by sweating and
respiration, and waste materials in the urine and faeces.
Factors affecting this loss are:
 Bodily condition
 State of repleshion
 Season
 Duration of transport
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Losses during 24 hours transport:
Pigs: 2.2-5.4 kg
Sheep: 3.6 kg
Calf: 4 kg.
The estimated actual loss in flesh in bacon pig is about 0.9 kg for
every day of journey and probably both muscular and fatty tissues
are affected with an abnormal loss of water from muscles.
Under stress pigs loose 6-7 per cent of live weight.
It is possible to restore some if not all of this loss with adequate rest,
drinking water but no feed for 24 hours.
In pigs sprayed with fine spray of cold water in an uncovered lorry,
weight loss was reduced by almost 50 per cent.
Humidity and temperature are also involved in the development of
DFD meat in cattle, the incidence of which seems to be greatest
during the cold days (winter).
Weight loss is greater in male than in female pigs (gills) (fighting
disposition of males).
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AFFECTIONS INDUCED BY FEVER
 Transit or shipping fever
Cattle under poor condition have become fatigued by long journey
(few foods in cold weather).
(Pneumonia, death, viral-bacterial infections, parainfluenza, P.
haemolytica, multocida, acute enteritis).
Early slaughter is adviced before the onset of septic lung changes.
 Transit tetanus
Under similar conditions in cows and ewes (advanced pregnancy).
Non-specific post-mortem lesions.
 Salmonellosis
In young calves and lambs may be precipitated by transport stress
(plus lack of food and water and by chilling).
The application of intensive methods in husbandry results in an
increase of Salmonellosis. Stocks of different origin are crowded
together open the possibility of spreading of infection.
It has found that there is a marked increase in the excretion of
Salmonellae by pigs and poultry after transport due to stress.
Miscellaneous conditions following transport of pigs include:
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Heat shock
Indigestion
Abortion
Ketosis
Foot diseases
Enterotoxaemia
Mastitis
Gastric ulceration
Infertility
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RESTING IN LAIRAGE
Fatigued and excited animals should be rested before slaughter, at
least for 2 hours.
An inadequate rest period may reduce the keeping quality of the
flesh because of incomplete development of acidity of muscles
resulting in an early invasion of the system by putrefactive bacteria
from the intestinal tract. These bacteria are responsible for bone taint
in cattle and ham taint in pigs.
Aggressive animals and females in oestrus must be isolated as must
horned from polled stock.
The actual duration of resting period depends on several factors:
species of animals, age, sex, condition, season, length of journey,
events and method of transportation.
Cows in good condition in temperate countries should not be held for
long periods during winter in lairage because of the possibility of
hypomagnesemic tetani.
Facilities should be checked to ensure that there are no defects
which could cause bruising or even death
Mixing of animals from different origins leads to fighting and injury.
The use of fine sprays of water on pigs waiting for slaughter in
lairages has beneficial effect in the prevention of fighting.
PURPOSE:
To arrange for slaughter of physiologically normal animals without
any loss of weight as soon as possible.
Rest before slaughter is beneficial but undue holding in lairages may
increase the numbers of certain organism in animals (Salmonella).
Contamination with excreta is the main hazard in lairages. 24 hours
rest seems to be adequate.
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WATERING
Animals should receive ample drinking water during their
detention in the lairage:
 To lower the bacterial load in the intestine
 Facilitates the removal of the hide or pelt during dressing
of the carcass
 Stunning the animal by electrical means becomes more
efficacious.
FEEDING
Traditional believe is among butchers all around the world that
fasting is beneficial prior to slaughter (bleed better, easier to dress
the carcass, having brighter appearance). No scientific evidence for
this believe. Hungry animal does not settle as well as an animal that
has been fed. Resistance to shock at low atmospheric temperature is
greater in the fed animal.
Pigs rested for 24 hours after a journey do not regain normality
unless they are fed.
As an extreme, the fatigue state and restlessness of hunger pigs may
render the flesh unsuitable for preserved meat products. Thus, there
are convincing reasons for avoiding thirst, hunger and fatigue in
animals waiting for slaughter. There is, however, justification
witholding food from cattle for a period of 6 hours prior to slaughter
as it minimises the emigration of bacteria from the intestinal tract
during digestion.
FASTING
This is the other side of the same coin: fasting contra feeding.
The purpose is to ensure the physiological normality in animals
before slaughtering by feeding if necessary.
However, there is also a duty not to present animal for slaughter with
full stomach in order to prevent carcass contamination:
 Wet hides and fleeces encourage the transfer of faecal material
particularly in areas of shanks, brisket and hocks
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Full stomachs cause extensive contamination of carcass and offal if
accidentally cut during the dressing procedure.
PRE-SLAUGHTER FEEDING OF SUGAR AND PIG MEAT QUALITY
AND YIELD
Muscle glycogen is an essential component of meat. Its presence
ensures an adequate amount of lactic acid after slaughter and
consequently low pH. Thereby, the meat gains good appearance,
taste tenderness and keeping quality.
If muscle glycogen is reduced by stress, a raised pH may lead to
poor keeping quality as well as DFD or PSE meat. Bacterial spoilage
tend to occur more rapidly in such a meat while normal (non DFD or
PSE) meat tends to sour.
The task, therefore, to minimize the depletion of muscle glycogen by
reducing stressor, adequate pre-slaughter rest may replenish the
glycogen loss due to travel.
Thus, feeding sugar (in solution) before slaughter increase meat
quality and also the efficacy of curing will be better and less shrink of
meat occurs while maturing.
LAIRAGE HYGIENE
The purpose is to prevent any further contamination of feet, hides
and skins.
 Solid, non-slip floors, suitably sloped to adequate drains
 From slotted floors are difficult to remove manure and disinfect
(movable slats, expanded metal).
 Adequate hose points should be placed and sufficient pressure
and volume of water
 Excessively long periods of retention only make the task of lairage
cleansing more difficult: cross-infection (Salmonella)
Spraying of animals with jets of water and walking through foot
bath before entering the slaughtering area is useful at countries of
warmer climate. Animals with long hair because of the built up of
manure and dirt on the hair, spraying makes matters worse (chemical
defleecing agents: individual variations in response).
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SOURCES OF BACTERIAL CONTAMINATION
The main source of carcass contamination is the live animal itself
particularly in winter months when animals are housed. In live
animals microorganisms are present:
 On the skin and hair
 In the natural orifices
The alimentary tract, nasopharyngial cavities and external portion of
the urogenital tract harbour characteristic bacterial flora that has
adapted to the particular environmental conditions.
Tissues and cavities that have no direct connection with the exterior
are considered to be STERILE. Provided, the animal is healthy and is
in good physiological normal condition there should be no bacteria in
the blood stream, bone marrow, lymphonodes, or the thoracic or
abdominal cavities, including lungs, liver and spleen. Bacteria play an
important role in the spoilage and decomposition of meat and also in
food poisoning.
Bacterial contamination of meat may occur:
 Pre-slaughter condition of animal largely determines the microbial
stage of the carcass. In weakened animal long journey, and in
general, stress may result in early invasion of blood vessels by
microorganisms from the intestines. In addition, high pH of the flesh
from exhausted or ill animals favors bacterial growth and reduce
carcass durability.
 During sticking, bacteria can enter the jugular vein and travel to the
muscles, lungs and bone marrow. The importance of this possibility
is questionable.
 Under ordinary conditions, the heaviest and potentially the most
dangerous load of bacteria is in the animals’ digestive tract. One
possible and serious source of contamination from digestive material
is the regurgitation that occurs when cattle are stunned and bled
causing severe contamination of the neck, throat and tongue (An
average of 45% of samples contained Salmonella organisms in a
study).
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 Contamination of the surface of the dressed carcass with bacteria
from the outside of the hide is of considerable importance. The type
of hide bacteria is dependent on the soil of the pastures. Stall-fed
cattle in winter may carry considerable dung on their hides.
 Actual contamination with dirty hands, clothing or equipment is
another important factor as well as from unhygienic knife sheets.
 Irrespective if cattle are dressed horizontally or on the line, the
most important sources of contamination are from the digestive tract
and the skin. In carcasses dressed horizontally, the highest bacterial
contamination is found on the belly and legs, while in those dressed
on the line the highest contamination is on the belly and shoulders.
The higher the carcass is suspended the lower is the bacterial
contamination of the carcass surface (The slaughter house floor
never touched!). However, the more intense the productivity of the
meat plant the greater is the Salmonella hazard and any error of
hygiene in the chain of production may have serious and widespread
consequences.
 Muscles may be influenced before slaughter by specific organisms
responsible for illness of the animal with the risk of bacterial food
poisoning in man.
 Otherwise, routine bacteriological procedures are of great value in
assessing the degree of surface bacterial contamination in abattoirs
and meat processing plants.
 Possible sources of bacterial contamination are: hide, hair, soil,
gastrointestinal content, water, airborne pollution and equipment
(knives, saws, cleavers, hooks, wiping, cloths, brushes).
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METHODS
OF
CONTAMINATION
LIMITING
OR
REDUCING
BACTERIAL
 Soft or loose dirt is removed by overhead spray in warm climates
but if faecal material is thickly adherent to hides and fleeces such a
practice only makes matters worse. For proper carcass dressing
hides and skins must be dry. Measures to reduce contaminations
in the abattoir begins at the farm continued on transportation, in
the markets and the lairage of the abattoir.
 In modern works, cattle are bled while suspended
 The oesophagus ligatured to prevent regurgitation of stomach
contents
 Cattle head are usually removed on the bleeding rail, the head is
skinned and washed with high pressure water spray
 A circular cut is made around the anus and the rectum is closed by
a plastic bag, secured with an elastic band.
 The hide puller should operate with downward action
 The floor, walls, hooks and inspection tables must inevitably
become contaminated and only intensive cleaning under mechanical
pressure is efficient to reduce bacterial load and disinfection is
applied. Wood tools cannot be cleaned satisfactorily nor can pit
floors or rusted iron hooks. The possibility of condensed water to be
formed must also be excluded.
SCALDING AND PRESSURE CLEANING
Floor, tools, equipment to achieve low bacterial count.
Knife sheets
A one -piece of stainless-steel sheet is recommended, no plastic!
Washing of the dressed carcass
A fine spray of water materially reduce the bacterial load of the
carcass (15-70 C, 0-20 psi, 5 sec-2.5 min per carcass).
The use of chlorinated water was found too beneficial (15-350 ppm).
Carcass must subsequently be dried and chilled to obtain maximum
benefit from spraying. If they are not chilled, keeping quality may be
reduced.
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Washing of edible offal
Liver, kidneys, hearts, thin skirt and tails are another important facet
of appropriate abattoir hygiene with a continuous flow of clean water
(For tongue a special device is: rotating metal drum with a through
flow of water-like cement mixer without the central agitator arms).
Hand washing facilities and “sterilizers”
Those should be in adequate number. The taps should be not hand
operable. Water should be sufficiently warm and bactericidal soap
along with disposable towels should be provided (bin for used
towels).
For knives, a small tank containing water at a temperature of at least
82 C can be attached to the side. Steam is not produced from the
“sterilizer”. Knives must be washed before “sterilized” (otherwise a
thick-soup will develop in the “sterilizer”).