The document discusses factors that influence the nutrient requirements of poultry. It lists many genetic, environmental, management, and health factors that can impact a bird's nutrient needs. These include the bird's genetic makeup, diet composition, temperature, housing type, intestinal health, presence of toxins or parasites, and stress levels. The document also discusses how nutrient requirements can be affected by nutrient interactions and deficiencies as well as diseases. Nutrition influences egg quality traits like shell thickness, albumen quality, pigmentation, and size. Maintaining proper calcium and phosphorus levels is important for bone health and growth performance in broilers.

1. Factors influencing the nutrient
requirements of poultry
Presented by:
Dr J. BalaKesava Reddy,
GVM/16-005,
Department Of Animal Nutrition,
NTR College Of Veterinary Science.

2. The factors that can influence the bird’s need for
nutrients are:
Genetic make-up of the bird,
Energy content of the diet (a major factor influencing feed intake),
Environment temperature (another factor influencing feed intake as
well as acid-base balance),
Type of housing (cage, wire or litter floor),
Nutrient availability from particular feedstuffs,
Influence of intestinal pH and transit flow on the destruction or
sequestering of dietary nutrients,
Presence of dietary oxidizing fats, especially in the presence of
catalyzing minerals and lack of antioxidants,

3. Influence of intestinal parasites,
Beneficial or detrimental intestinal bacteria,
Fungal toxins in feedstuffs (eg. Aflatoxins and other mycotoxins),
Nutrients made unavailable to the bird through colloids in
ingredients, or adverse interactions with other nutrients in the
intestinal tract.
Nutrient destruction in feed or drinking water by nitrites, sulfites or
other chemicals,
Destruction of nutrients by ultraviolet light,
Positive or negative effects of enzymes found in ingredients,

4. Decreased absorption due to damage to absorptive cells, lack of
digestible fat, or bile,
Competition for absorption due to nutrient imbalances or lack of
factors needed for active nutrient absorption,
Influences of intestinal bacteria in nutrient biosynthesis,
Presence of antimetabolites in certain feedstuffs,
Nutrient interrelationships (eg. lysine:arginine)
Influence of hormones in the bird, and from animal byproduct
ingredients,
Effect of disease and environmental stress factors,
Restricted feeding - imposed either as a management tool or an
effect due to limitations of feeder space.

5. WELL KNOWN INTERRELATIONSHIPS
A number of nutrient interrelationships are well known and the
manner in which they affect requirements has been relatively well
established.
These include:
a) Energy: protein ratio;
b) Interaction of calcium, phosphorus and vitamin D3;
c) Niacin, tryptophan relationship;
d) Choline, methionine, folic acid and vitamin B12 relationship in methyl
group metabolism and transmethylation reactions;

6. e) Involvement of vitamin E, selenium and cystine in the prevention of
exudative diathesis and muscular dystrophy in chicks;
f) Chelation effects of certain amino acids and minerals in the transport
of specific nutrients;
g) Numerous trace mineral interrelationships such as copper and zinc,
zinc and cadmium, copper and molybdenum, and selenium and
arsenic;
h) Amino acid interrelationships such as lysine:arginine, leucine,
isoleucine and valine and specific amino acid imbalances and
antagonisms.

7. NUTRITION AND GENETICS

8. Variations in requirements for specific
nutrients:
Quantitative requirements have been reported to vary between
breeds or strain of chickens.
Heavy breeds seem to require more vitamin E to prevent encephalo-
malacia .
Workers at Cornell were able to select two strains of White Leghorns
that differed in their response to riboflavin and lysine.
Also breed differences have been reported for pantothenic acid,
pyridoxine and choline.

9. Size of bird will also have a noticeable effect on the requirement for
certain nutrients.
The heavy broiler breeder will be partitioning a greater percentage of
her nutrient intake into maintenance as compared to the smaller high
egg output strains of White Leghorn.
Also the physiological makeup of the dwarf bird with its slightly lower
body temperature and reduced metabolic rate accounts for the small
differences in nutrient requirements for this bird as compared to
normal sized birds.

10. Specific metabolic variations:
A number of individual metabolic variations exists and many of these
variations have an effect on nutrient requirements.
An example is phenyl ketonuria, a condition in which the conversion of
phenylalanine to tyrosine is diminished because of limited synthesis of the
enzyme phenylalanine hydroxylase.
There are specific inherited metabolic abnormalities that have been detect-
ed in chickens, including hens that lay eggs almost devoid of riboflavin
regardless of the level found in the diet.
Camaghan et al. (1967) and Smith and Hamilton (1970) reported marked
differences in the susceptibility of birds to aflatoxin, with brown egg breeds
being more susceptible than are White Leghorns.

11. NUTRITION, DISEASE AND STRESS

12. The development of the poultry industry during the past half-century
has been due in part, to the ability of the chicken to accommodate
many of the stresses imposed on them by modern production
techniques.
Such stressors include genetic selection for increased rate of growth
and egg numbers, environmental and management changes,
increased disease challenges and exposure to a wide array of
pharmaceuticals and vaccines needed to maintain flock health.

13. The metabolic changes in chickens associated with response to
external stressors are:
1. Enlargement of the anterior pituitary gland, probably due to the
increased production of adrenocorticotropic hormone (ACTH),
2. Adrenal hypertrophy with increased output of corticosterone,
3. Atrophy of the thymus, Bursa of Fabricius and the spleen. The
regression of the Bursa of Fabricius is the most sensitive indicator of
stress in young birds.
4. Changes in the circulating leukocytes, with a decrease in
lymphocytes and an increase in heterophils,
5. Slower growth or weight loss.

14. Parasites and nutrition:
The intestinal tract of a chicken provides an ideal habitat for microorganisms includ-
ing bacteria and protozoa which may be parasitic.
The presence of microorganisms in the digestive tract cause a number of anatomical
changes, the most notable being a longer and heavier tract than is found in germ-
free chickens.
There are differences in the epithelial cells, the amount of lymphatic tissue of the
lamina propria and pH of the duodenal contents of conventional versus germ-free
chickens.
Also, there is a difference in bile acid secretion with greater amounts occurring in the
conventionally reared birds.
The lower part of the small intestine, and especially the ceaca, contain more volatile
fatty acids as well as such compounds as ammonia and pharmacologically active
amines in the conventional bird while these are virtually missing in the germ-free
animal.
The ceacal contents of the conventional bird also contain a wide array of the B-
vitamins although these seem to contribute little to the vitamin requirements of the
bird (Coates et al., 1968).

15. Protozoans and particularly coccidia have marked effects on the digestive
physiology of the host.
They have been shown to result in significant damage to the intestinal wall,
and so reducing the absorption of a number of nutrients (Turk, 1974).
Crompton and Nesheim (1976) reviewed the work reported on the effect
of coccidia on vitamin A requirements.
Chicks fed diets low in vitamin A showed higher mortality together with
reduced liver storage of vitamin A and reduced pigmentation.
There are a number of other studies demonstrating alteration in the
absorption of amino acids and certain minerals when birds harbour
coccidial oocysts.
In essence, coccidia, due to capillary cell damage, reduce the absorption of
most dietary nutrients.

16. Nutrition and other diseases:
It has been shown experimentally that low levels of dietary vitamin A
appear to accentuate the severity of lesions caused by infection with
mycoplasma and infectious bronchitis.
It has also been demonstrated that high levels of dietary vitamin A
will reduce the severity of lesions and mortality due to coccidiosis.
This phenomenon implies that natural feedstuffs may contain
unknown nutritional factors which aid in overcoming environmental
stress and infectious disease.

17. Folic acid deficiency causes a marked reduction in the number of
white blood cells because this vitamin appears to be needed for their
synthesis.
A deficiency of folic acid not only weakens the animal because of
resultant anemia, but also because of associated loss in the number
of white blood cells.
The adrenal cortex has a marked effect on the resistance of an animal
to a number of diseases.
Vitamin C, folic acid and vitamin B12 are known to be concerned with
the functioning of this gland.

18. NUTRITION AND EGG QUALITY

19. Egg quality encompasses a wide range of physical and chemical
properties that interrelate to ultimately produce a high quality egg.
These are:
1) Shell quality,
2) Albumen quality,
3) Nutritional composition,
4) Freedom from defects such as blood spots, mottling, etc.,
5) Yolk pigmentation, and
6) Egg size.
Most of these parameters can be influenced by a wide range of
dietary situations and nutrient interrelationships.

20. Eggshell quality:
White or brown shelled eggs are preferred in different markets.
Shell color is dependent on the quantity of pigments secreted from the
shell gland during the final stages of calcification and is generally
independent of normal bird nutrition.
Shell color has no effect on the nutrient composition of the egg.
However, inadvertantly feeding the anticoccidial Nicarbazin® causes
almost complete loss of pigmentation of brown shelled eggs.
Feeding high levels of chlorotetracycline antibiotics causes a characteristic
yellow coloring of white shelled eggs.

21. Eggshell thickness is the most important feature of shell quality and
the major nutrients involved are calcium, phosphorus and vitamin D3.
When shell quality (thickness) problems persist, it is common
practice to feed more calcium, vitamin D3 or a combination of these
nutrients.
Unfortunately feeding an excess of these nutrients can cause
excessive particulate calcium deposits on the shell.
These extra calcium deposits may be reason for downgrading in some
markets, and are also prone to separation from the shell surface
causing a potential route of entry by bacteria.

22. Albumen quality:
The grade of table eggs depends to a major degree on the firmness or gel
structure of the albumen.
The protein in egg albumen most associated with the gel structure is
ovomucin.
This protein fraction of eggs is apparently heterogeneous and is composed of
two or more fractions which may vary markedly in carbohydrate composition
(Smith et al., 1974).
There is a positive correlation between Haugh units and ovomucin content of
fresh eggs.
Those eggs with a firm albumen that have high Haugh unit values have greater
quantities of ovomucin.
Eggs examined in the isthmus of the oviduct have similar quantities of
ovomucin even though eggs may be laid with varying albumen quality.
Major changes in the ovomucin content of eggs seem to occur in the shell
gland, likely due to plumping with water and solutes.

23. Feeding ammonium chloride causes an increase in albumen height
and the amount of thick white.
Austic (1977) found that feeding hens a diet containing ammonium
chloride increased the Haugh units of freshly laid eggs and also
caused an increase in the ovomucin content of the eggs.
The mechanism responsible for these effects is not known although
the influence of ammonium chloride may be mediated through slight
changes in egg pH.
Although ammonium chloride feeding can increase albumen quality,
it also causes a reduction in blood pH and reduced egg shell
thickness.

24. Egg defects caused by nutritional problems:
Blood spots are one of the most significant defects in eggs that cause
considerable economic loss.
The clots may be very small or may be large enough to cause
discoloration of the entire egg.
Although blood spots do not adversely affect the nutritional value of
eggs, they are very objectionable to consumers.
The major nutritional factor known to affect blood spot formation is
vitamin A deficiency, which usually causes a marked increase in their
incidence in eggs.

25. The feeding of Nicarbazin® to hens results in a characteristic mottling
of the yolk.
Yolk mottling has also been reported from feeding a combination of
the worming drugs piperazine, phenothiazine and dibutyltin dilaurate
to laying hens.
Individually, these drugs seem to have no effect on egg yolks.

26. Nutrition and egg size:
The size of an egg is controlled by many factors, including genetics, stage of
sexual maturity, age, some drugs, and some dietary nutrients.
The most important nutritional factors known to affect egg size are protein
and amino acid adequacy of a diet and linoleic acid.
A striking reduction in egg size can be produced by a linoleic acid
deficiency.
In a severe deficiency, eggs laid by mature hens may weigh only about 40
grams compared with a weight of 60 grams for eggs from control hens.
Under practical conditions, the linoleic acid content may be marginal in
diets containing low levels of corn and no added fat.
Improvements in egg size related to linoleic acid have been observed when
hens are fed diets composed primarily of barley, wheat or milo as grain
sources.

27. INFLUENCE OF DIETARY CALCIUM CONCENTRATIONS AND
THE CALCIUM-TO-NON-PHYTATE PHOSPHORUS RATIO ON
GROWTH PERFORMANCE, BONE CHARACTERISTICS, AND
DIGESTIBILITY IN BROILERS
A. E. Gautier, C. L. Walk, and R. N. Dilger
(2017 Poultry Science Association Inc).

28. Two experiments were conducted to determine the influence of dietary Ca
concentrations(Experiment 1) and a combination of dietary Ca and non-phytate
phosphorus (NPP) to create distinct Ca to- NPP ratios (Experiment 2) in corn-
soybean meal diets fed to broiler chickens from 2 to 23 d of age.
In Experiment 1, dietary treatments consisted of 7 concentrations of Ca (0.4, 0.6,
0.8, 1.0, 1.2, 1.4, or 1.6% of the diet; 7 treatments total), and NPP
concentrations were maintained at 0.3%.
Increasing the dietary Ca concentration while maintaining 0.3% NPP elicited
linear reductions (P < 0.01) in overall growth performance and tibia ash.
Dietary effects also were observed for apparent retention of P and Ca, which
decreased (P < 0.05) linearly or quadratically for birds receiving dietary
treatments with Ca concentrations greater than 0.6%.
In Experiment 2, diets were formulated to contain 3 concentrations of Ca (0.4,
1.0, or 1.6% of the diet) with NPP concentrations either constant at 0.45% or
adjusted to maintain a dietary Ca-to-NPP ratio of 2:1 (6 treatments total).

29. Growth performance was not influenced by Ca concentration or the
Ca-to-NPP ratio.
Tibia break force was lower (P < 0.01) in birds fed diets containing
0.4% Ca, regardless of the NPP concentration.
Tibia ash increased (P < 0.01) as the dietary Ca concentration
increased.
Neither the dietary Ca nor NPP concentrations affected nitrogen
retention (P > 0.05).
Conclusion:
Imbalanced Ca and NPP adversely influenced growth performance
and nutrient retention of broilers, indicating the concentrations of Ca
and NPP required to maximize bone structure and function may be
higher than those required for performance.

30. References:
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