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Feeding Standard
-amount of nutrient required by animals
-it may be expressed as quantities of
nutrients or in dietary proportions
-standards may be provided separately for
each process of the animal or as overall
figures for combined processes.
-addition of safety margin is involved in
the translation of requirements into
allowances that are used in feeding
practice.
-should be considered as guides to feeding
practice and not as flexible rules:
1. They don’t replace the art of the
farmer in the finer adjustment of food
intake to animal performance.
2. The application of feeding standard
is not restricted to individual animals
3. Can be used at farm scale to
calculate feed requirement or used at
national level to assist planning of food
imports.
-Commercial companies, main users of
feeding standards because they supply
concentrate and often modify feeding
standards from one generation to another
because of the speed of genetic selection
and improvement.
-the greater the variety of feeding
standards available the higher the
tendency for them to be frequently
revised.
Safety Margin
-designed to ensure that no animals, or
only those with an exceptional high
requirement, will be underfed.
-Also, it is often added to requirement
when calculating the allowance fed.
-The larger the variation the greater the
safety margin.
Nutrient Requirements for Maintenance
1. State of Maintenance – when animal’s
body composition remains in constant
and doesn’t give rise to any product and
doesn’t perform any work on its
environment.
-Animals deprived of food are forced to
draw on their body reserves to meet their
nutrient requirements for maintenance.
2. State of Negative Energy Balance – the
energy utilized leaves the body in the
form heat.
e.g Negative Nitrogen Balance
Maintenance Requirement
-the quantity required to ensure that the
animal experiences neither gain nor loss of
that nutrient.
-promotes minimum quantity of zero
balance
Units and Terminologies
A. Gross Energy – total energy release by
heat combustion
B. Digestible Energy – GE of the feed minus
GE of the feces
C. Metabolisable Energy – DE minus energy
excreted in urine and as combustible
gases.
D. Net/Final Energy – ME minus heat
increment.
E. Heat Increment – heat produced during
digestion of feed, metabolism of nutrients
and excretion of waste.
F. MJ – Mega Joule
G. DCP/MP – Digestible Crude Protein or
Metabolisable Protein
H. CP- Crude Protein
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Basal Metabolism = NE
-energy expended in the maintenance of
an animal leaves the body in the form of
heat.
-the quantity of heat arising this way is
animal’s basal metabolism.
-it is the measurement provides direct
estimate of the NE that the animal
requires from its food in order to meet the
demands of maintenance.
Factors affecting Basal Metabolism
a. Heat in maintenance
b. Heat increment (Food deprivation)
c. Voluntary Muscular Activity
d. Cold environment
Criteria for Post – Absorptive State
a. Decline in heat production to a steady
constant level
b. Respiratory quotient
c. (Ruminants) decline in methane
production to very low level.
Fasting Metabolism =
-used in preference to basal metabolism
-fasting catabolism, relatively small
quantities of energy lost by fasting
animals in their urine.
-fasting metabolism, proportional to the
metabolic liveweight of the animal.
-small animals, has higher fasting heat
production, higher heart rate and more
susceptible to environment factors.
-fasting heat production is related closely
to the surface area of animals than to their
weight.
Fasting Metabolism…
-the fasting metabolism of adults
animals have an average value of
and
the
approximate
equivalent
is
.
-cattle, 15% higher fasting metabolism
than interspecies mean.
-sheep, 15% fasting metabolism lower
-young calf,
fasting
metabolism per unit liveweight.
-mature cow,
fasting
metabolism per unit liveweight
Factors affecting Fasting Metabolism
a. Surface area/Size
b. Age (younger has higher fasting
metabolism per unit of metabolic
liveweight)
c. Sex (M 15% higher than female
&castrate)
Energy Balance and Feeding Trials
-the energy required for maintenance
promotes zero balance.
-zero balance, can be estimated
directly in fed, as opposed to fasted,
animals if the energy content of their
food is known and their energy
balance can be measured in feeding
trials.
-in theory the quantities of food given
could adjusted until animals were in
the exact energy equilibrium.
ME = (DM*M/D)–(MJ per Day / kgDM)
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DM – Dry Matter ; Kg –gain in constant
M/D – ME per diet or
Energy Balance and Feeding Trials…
-animals are given known quantities of
food energy, and their liveweight and
liveweight gains or losses measured.
-the partition in energy intake between
that is used for maintenance and that is
used for liveweight gain can be made in
two ways:
1. Use of known feeding standard for
liveweight gain.
2. Use the figures for energy intake (I),
liveweight gain (G) and a & b for estimates
of the quantities of food energy that is
used for maintenance and for each unit of
liveweight gain.
-Feeding Trial, takes advantage of energy
content of feed.
-Used to estimate the quantity of energy
needed to promote energy equilibrium in
maintenance
-the main objection to using feeding trials
to
determines
requirements
for
maintenance (also for production), is that
liveweight gain is relatively poor measure
of energy balance.
Fasting Metabolism as Basis for
Estimating Maintenance Requirements
-Feeding trials, method of estimating
maintenance requirements and has the
advantage of being applied to animals
kept under normal farm conditions.
-additional activity hinders the effect of
feeding trials.
Factors that affects FM as basis for
estimating MR
a. Animals in the farm use more energy
for voluntary muscular activity
b. Productive livestock must operate
with higher metabolic rate than fasted
animals and thereby incur higher
maintenance cost.
c. Farm animals experience greater
extremes of climate.
-to find the maintenance required it
was derived that
.
Fasting Metabolism as Basis for
Estimating Maintenance Requirements…
-the energy cost of eating (prehension,
chewing, swallowing) and rumination are
included in the heat increment of feeding.
–grazing animal, energy requirements for
muscular activity will be much increased.
-grazing animal tend to have 25-50%
greater than those of housed animals.
-actual increase will depend on the terrain
and vegetation type.
- the value obtained for a particular animal
depends on the animal’s previous energy
status.
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-animals in high plane of nutrition
suddenly fasted, the metabolic rate will be
higher than similar animals previously kept
in lower plane.
-Ration, has to be progressively reduced to
maintain required equilibrium.
-FM was determined after the period of
low plane nutrition.
-when expressing FM it varies depending
on animal’s body composition.
-Active tissues and organs, require more
energy for maintenance.
-Fat animal, has lower fasting metabolism
than a thin animal of the same weight.
Inference to adapt low-level (Maintenance)
a. By improving their efficiency of energy
utilization.
b. By reducing non-essential muscular
activity.
Influence of Climate on Energy
Metabolism and Requirements for
Maintenance
-Climate, has the greatest influence on energy
requirements.
-Cold climates animal kept at or below the
maintenance level are most affected.
-Homeotherms, animals that attempt to keep
their body temperature constant.(Mammals &
Birds)
-the rate of heat loss is determined by
complex interaction of factors contributed by
both the animal and its environment.
-rectal temperature is lower than deep body
temperature that lies in the range of 36-43
Routes of Heat Loss
a. Sensible - losses by radiation, conduction
and convection from their body surface.
b. Evaporative – losses of water from the
body surface and lungs.
Factors that Affects the Rate of Heat
Temperature
a. Animal Characteristics – insulation
provided by the tissues and coat.
b. Environmental Characteristics – air
velocity, relative humidity and solar
radiation.
The Effect of Environmental Temperature on
the Heat Production.
a. Lower Critical Temperature
b. Upper Critical Temperature
c. Thermoneutral Temperature
1. Lower Critical Temperature
-environmental temperature in which the heat
production is increased.
-if the air temperature gradually reduced, the
pig will begin to lose heat more rapidly.
-as the fall in air temperature continues, the
way to maintain its deep body temperature by
increasing its heat production by:
a. in muscular activity (shivering)
b. in food intake (feeding)
2. Upper Critical Temperature
-temperature above which animals must
reduce their heat production.
-increasing temperature, would have difficulty
in losing heat by sensible losses and would
need to its evaporative losses.
-the animal would need to reduce its heat
production by:
a. Restricting its muscular activity
b. food intake
3. Thermoneutral Zone
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– range between upper and lower critical
temperature wherein the temperature of an
animal is in neutral.
The Effect of Environmental Temperature
on the Heat Production of RUMINANTS
-ruminants, have wider thermoneutral
zone and lower critical temperature
-has greater capacity to regulate
evaporative heat losses and their heat of
increment is higher.
-ruminants tend to produce heat constant
throughout the day.
-Non-Ruminants, tend to digest and
metabolise their food quickly and then
experience cold when heat increment has
declined
-Smaller Animals, tend to be more
susceptible to cold because they are often
less well insulated (less fat and coating).
-however this is balanced having a higher
basal metabolic rate per unit of body
weight.
(in light to this,
the lower critical
temperature of an adult sheep is higher
than a cow, wherein they are kept in the
same environment)
-An animal’s insulation depends on its
subcutaneous fat and coat depth. Thus, a
sheep that has been shorn is particularly
vulnerable to cold, even summer, and
especially if it is deprived of food
-Housed animals, insulation depends on
the type of floor and group size. Pigs kept
on straw have lower critical temperature
than pigs kept in concrete. Pigs kept in
groups can huddle together to reduce
their surface area and lower critical
temperature.
-Rain, increases heat loss both by reducing
insulation and through the heat
vaporization.
-Farm animals that are most likely to suffer
from cold stress are newborn lambs,
calves and pigs because they are small and
tend to have poor insulation.
-If they fail to obtain sufficient milk from
their mother, heat increment of feeding
will be low.
-Brown adipose tissue, used by new-borns
for generating heat soon after birth. The
amount of reserves is relatively small and
its protective role is limited.
-Young animals, should receive food in the
form of colostrum and milk.
Strategies for Alleviating Cold Stress
(Management wise)
a. Make environment warmer
b. Allow animal to increase its heat
production from existing resources
(metabolizing fat reserves)
c. Increase
heat
production
by
manipulating its diet
(Animal)
a.
b.
muscular activity
of food intake (heat increment)\
Rate of increase of heat loss for every
fall of




Adult Pigs – 18 KJ per kg of
Poultry – 14 KJ per kg of
Pigs and Poultry – (10-20 KJ)
Ruminants (Outdoors) - (20-40 KJ)
-Laying hens, normally fed to appetite
therefore are able to adjust their food and
energy intake to regulate body
temperature.
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-Ruminants, are possible to influence heat
production by changing the quality of diet.
-ME derived from low-quality forage-based
diets is used with a lower efficiency (k)
than
derived
from
high-quality
concentrate-based diets.
In hot climates
-animal’s problem is one of disposing of the
excess heat it produces.
-Domestic spp, vary in the ability to lose heat
by means of evaporation of water.
-Mammals(most), poorly equipped w/ sweat
glands
-Birds, do not have sweat glands.
-Cattle, able to lose quantities of water and
heat by sweating.
-As temperature increases, sensible heat loss
reduce and more heat is lost by evaporation.
-Some animals tend to lose heat by sweating
(Bos indicus) but major route is the respiratory
tract.
-If animal’s own heat loss mechanisms
become overtaxed, the animal has to reduce
its heat production, which it does by reducing
its food and energy intake.
e.g Wallowing – rolling or lying in mud or
bodies of water.
FACTORS FEEDING STANDARDS FOR
MAINTENANCE (ENERGY)
Ruminants
-Fasting Weight, predicted from liveweight by
dividing 1.08 (wherein 1.08 is maintenance
allotted for activities).
-Bulls, 15% FM than steers and heifers
-0.0071 W (growing cattle)
-0.0095 W (lactating cattle)
-0.0067 W (housed fattening lambs)
-0.0024 W (hill grazing lambs)
-0.714 (maintenance/NE)
-(↑ME maintenance→ ↓NE maintenance)
-Empty Body Weight (EBW), slaughter weight
and weight were visceral/ internal organs are
not included.
Key factors:
a. Type of Ruminant (Small or Large) and
Type
of
Species
(Production
dependent)
Ex.
Bos taurus = 1.4, common in temperate
environment, has higher protein requirement
Bos indicus = 1.2, dairy, common in tropical
climate
b. Sex (Males have higher maintenance)
c. Maintenance
d. Age
e. Production (Additional)
f. Graze (Additional)
g. Environment
(Cold
vs.
Hot)
(Additional)
Swine
Factors:
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a. Sex (Boars have higher maintenance
requirement
-15% than sows
b. Body Composition
-Pigs, are more efficient in muscle build up and
less efficient in milk production.
Poultry (laying hens)
Factor:
a. Production
Equine
Factors:
a. Docile Adult < Alert/Active Adult <
Active
Young
(Maintenance
Requirement)
-Docile (0.126 W)
-Alert/active (0.139 W)
-Young (0.152 W)
b. Body Composition
c. Type of Activities
(Light, Moderate, Heavy, and Very Heavy)
PROTEIN
REQUIREMENT
FOR
MAINTENANCE
- If an animal continue to eat nitrogen-free
feed but otherwise adequate diet, it will
continue to lose nitrogen in its faeces and
urine.
*Metabolic Faecal Nitrogen – nitrogen in
faeces consisting of enzymes and sloughed
cells arising from the digestive tract, and from
microbial residues (not used nitrogen)
*Endogenous Urinary Nitrogen – this
excretion represents nitrogen that has been
incorporated into materials that are
subsequently expended and cannot be
recovered for reuse within the body
- are those that are metabolically the most
active and where the proteins are most liable,
such as liver
-Once the reserved protein has been depleted,
urinary nitrogen excretion reaches a minimal
and
approximately
constant
level
(Endogenous Urinary Nitrogen). However, this
level will maintain only if energy intake is
adequate.
-Endogenous Urinary Nitrogen can be used to
estimate
the
nitrogen
(or
protein)
requirement for maintenance
- The total or basal endogenous nitrogen is
calculated as the sum of endogenous urinary
nitrogen and metabolic faecal nitrogen
-When nitrogen is reintroduced into the diet,
the quantity of nitrogen excreted in the urine
increases because of the inefficiency of
utilisation of amino acids derived from the
diet.
-Exogenous urinary nitrogen the urinary
nitrogen excreted in excess of the
endogenous component
- Quantity of nitrogen (or protein) required for
maintenance is that which will balance the
endogenous urinary and metabolic fecal
losses of nitrogen (and also dermal losses)
Ways to Measure Protein Maintenance:
 Fasting catabolism
 Feeding trial
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FACTORS
AFFECTING
FEEDING
STANDARDS FOR MAINTENANCE OF
PROTEIN
Ruminants
-Bos taurus has higher protein maintenance
than Bos indicus
-Basal endogenous nitrogen is 2 times higher
than non-ruminants
Swine
-It is possible to calculate the requirements of
these animals for maintenance alone from
endogenous losses
-Protein requirements for maintenance of pigs
can be met by supplying 0.9g of standardised
ileal digestible protein per kg W0.75 per day.
Poultry
-production (through endogenous losses)
Equine
-In terms of crude protein
-More active horses have more lean tissue to
support
-Additional protein requirement for active
horses (because of muscle gain, sweat loss,
and dermal losses)
-Heavy activities of equine, results in higher
muscle gain and higher rate of sweat loss
NUTRIENT REQUIREMENT FOR GROWTH
-Intensive (continuous supply of food and will
follow growth curve) vs. Extensive (Food
Scarcity or interrupted supply of food and will
follow more interrupted curves)
-As animal grow, not only they increase in size
and weight but also they show development
-Animal growth and animal nutrition are linked
together
-Purpose of animal affects the growth
-Fetal period to Puberty
-After puberty
CHEMICAL COMPOSITION OF GAIN
- Protein, water and ash (together with
essential lipids and carbohydrates) are
combined in relatively constant proportions to
form lean body mass of an animal. Animal
contains a variable proportion of storage
lipids. Both protein and lipid contribute to the
energy content of the body. In addition to
these integral components, the body also
contains the extraneous and variable gut and
bladder contents.
- In early life, the gain consists mainly of water,
protein and minerals (ash) required for
growth of bone and muscle; later, after
puberty, the gain contains a higher proportion
of fat and as a result its energy content
increases
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- EBW of animal leads to
weights of
chemical components that make body
increase at differing rates.
-Cattle, the maturity is based on weight and
not on age
-Early Maturing, increase in protein to
decrease in protein and increase in fat
accumulation (female)
-Late maturing, constant fat (male)
-growth after puberty is due to fat
-growth before puberty is due to protein
Factors Infuencing the Composition of
Gaining
a. Animal species (Within a species,
composition of gain will differ between small
and large breeds). Small species will gain more
in early maturing (proteins) while Large
species will gain more in late maturing (fats)
b. Body weight relative to the mature weight
of animal (Ex. Females pigs are smaller than
males at maturity, but at a specific weight
their gain contains more fat and energy than
that males)
c. Growth rate of animal (Immature animals
with limited nutrients for growth tends to
grow slowly because the body will use their
energy fort bone and muscle environment,
whereas animals with more nutrients available
will store fats)
-Ash, measurement of minerals and vitamins in
the animal’s body.
*Aberdeen – Beef
*Holstein – Diary
FACTORS FOR FEEDING STANDARDS FOR
GROWTH (Energy)
Ruminants
-The effects of breed and sex on EVg, a simple
15 percent correction factor has been
adopted.
Ex. 500 kg female of a small breed growing at
0.5 kg/day would be predicted to gain
19.9 x 1.15 x 1.15 = 23.3 MJ/kg
Standard Reference Weight (SRW) – mature
weight
Bull- 3 to 4
Cattle – 3
Key factors :
a. Sex
b. SRW
c. Type of breed / Late vs Early Maturing
Swine
-For energy requirement for growth of pigs,
there are 3 types given:
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
Exceptionally Lean and fast-growing =
maximum rate of protein retention ,23
kg/day
- Higher maintenance for activity
1.10-1.50
 Intermediate = maximum rate of
protein retention .17 kg/day
 Commercial = maximum rate of
protein retention .12 kg/day
-Males are more lean and fast-growing;
castrates are to be commercial types
-Fixed model for NE requirement = 0.75W 0.75 x
1.10 (1.10 = allowance for activity)
-energy content of protein (23.6 MJ/kg) and
fat (39.3 MJ/kg)
Poultry
-growing poultry are normally fed to appetite,
and nutrient requirements are therefore
expressed not as quantities required per day
but as the nutrient concentrations in the diet.
-the quantities of food eaten by poultry are
inversely related to concentration of energy in
diet. This means that change in energy
concentration should have corresponding
change.
Horses
-DE requirement for gain = (DE intake - DE
requirement for maintenance) / Daily gain
-For horse of 12 months of age, this equation
predicts that energy requirement for gain
would be 56.4 MJ/kg
FEEDING STANDARD FOR GROWTH
(PROTEIN)
Ruminants
Total Protein Requirement = Protein Req. for
Growth + Protein Req. for Maintenance
-For net protein req. for growth, the predicted
value increased by 10 percent for bulls and
large breeds and reduced by 10 percent for
heifers and small breeds
Ex. The NPg of a 300 kg bull of a large breed
gaining 1.2 kg/day.
128 x 1.10 x 1.10 x 1.2 = 186 g/day
Key Factors:
a. Sex
b. Size (breed)
c. Adjustment rate of gain or loss
d. Age (Young rapid growing
Pigs and Poultry
-In addition to the general req. for protein,
non-ruminant animals have a specific dietary
req. for the ten or so essential amino acids
-Req. may also be stated in terms of ‘ideal
protein’ or ‘standardised ileal digestible amino
acids’
-they will also take into account the availability
of certain amino acids, asserted from
digestibility at the terminal ileum.
- 3 Amino acid to formulate (lysine,
methionine+cysteine, threonine)
The Requirement of Pigs and Poultry for
Essential Amino Acids
-Phenyl alanine and tyrosine have similar
relationship and in chicks
-glycine and serine are interconvertable
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-Glycine increase by low concentration of
methionine, arginine and vit. B
-cystein can be synthesized by animal from
methionine (but not interconvertable)
-change in energy should correspond to total
protein and amino acid change
-first-limiting amino acid for pigs is lysine
-first-limiting amino acid for chicks is
commonly methionine, although lysine and
arginine may also be deficient
Horses (Crude Protein M. + Body Weight Gain)
-protein content of body weight gain is
assumed to be 20 percent and the efficiency
of utilisation of absorbed protein for gain is
assumed to vary with age of horse.
-first limiting amino acid for horse is lysine
-79% Ave. digestibility dietary protein
(standardized ilial activity)
NUTRIENT REQUIREMENT FOR WOOL
PRODUCTION
-wool is produced even in state of negative
(energy and protein) balance
-wool fibers are made entirely of protein
keratin, which is synthesized from the
essential amino acid, methionine
-methionine is also used by the follicles to
synthesize the polyamines required for
protein synthesis. Thus, wool follicles require a
good supply of sulphur-containing amino acids
(methionine, cysteine, cystine)
-Wool wax-produced by the sebaceous glands
and consists mainly of esters of cholesterol
and other alcohols, along with fatty acids
normally found in glycerides
-Suint-secretion of sudoriferous growth
glands, mixture of inorganic salts, potassium
soaps and potassium salts of lower fatty acids
-daily wool growth is predicted from either MP
available for wool production or ME available
for wool production, whichever is limiting, on
the assumption that wool growth is
maximised when the MP:ME ratio available for
wool production is 12 g/MJ.
-If ratio is less than 12 g/MJ, wool growth is
predicted from MP supply
-if ratio is greater than 12g/MJ, wool growth is
predicted from ME supply
-rate of wool production increases as plane of
nutrition increases and sheep gains weight
-diameter of wool fiber also depends on plane
of nutrition
-copper deficiency may restrict formation of
melanin, the pigment of wool and hair
-zinc deficiency causes the production of
brittle wool fiber.
- Wool production, requires continuous supply
of nutrients
-Even the animal is malnourished and in the
state of negative energy balance it can still
produce wool continually.
NUTRITIONAL CONROL OF GROWTH
-the rate of growth of an animal is described
as pacemaker of animal production, and both
natural and imposed variations in the animal’s
energy supply will be reflected in its growth
rate. A rapid growth rate is desirable because
it minimises the ‘overhead’ cost of
maintenance per unit of meat produced
-fat is no longer considered a desirable
component of meat. Control of growth is
often aimed at increasing muscle and reducing
growth
-Another way to prevent excessive fat
deposition is to treat animals with
‘repartitioning agents’; these are hormones or
related substance that alter partition of
energy bet. Protein and fat deposition. It
includes sex hormones (oestrogen and
androgens), somastostatin (growth hormone)
and cimaterol and clenbuterol
-Control of growth aims to maximise protein
deposition (lean tissue)
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-to ensure the correct partition of energy
between protein and fat deposition, it is
essential that protein supply should match
energy supply
-opportunities exist for controlling growth
through nutrition by phasing nutrient intake
(High-High, Low-High, High-Low, Low-Low)
-compensating animals often eat more good
per unit of body weight than others and may
deposit a higher proposition of lean tissue to
fat.
GOOD LUCK MGA FUTURE DOC!