NUTRITION V: POULTRY

Question 1

The poultry industry

Answer 1

• The poultry sector is possibly the fastest growing and most flexible of all livestock sectors
• Poultry meat does not contain the trans fats that contribute to coronary heart disease
• Eggs are an all-natural source of high-quality protein, vitamins and minerals
• No religious restrictions
• Cost-effective and versatile, the unique nutritional composition of poultry meat and eggs can help meet a variety of nutrient needs of children through older adults

Question 2

Laying hens perfomance Compared to 1960

Answer 2

• Egg production release 71% lower greenhouse gas emission
• 32% less water to produce a dozen eggs
• Half the. amount of feed
• 27%. more eggs. per day
• 330 eggs per year

Question 3

Digestion

Answer 3

is the break down of large complex compounds into smaller ones that are capable of being absorbed, e.g. protein is broken down into it’s constituent amino acids which are absorbed at the small intestine

Question 4

Absorption

Answer 4

is the passage of nutrients across cells lining the digestive system into the bloodstream. Mainly occurs at the small intestine in monogastric animals

Jejunum is the main place of digestion and absorption in poultry

Question 5

SCFA

Answer 5

The key metabolic end products of carbohydrate fermentation by intestinal bacteria are SCFA, such as butyrate, acetate, propionate, succinate, and lactate
In pigs, total energy obtained from SCFA producing hindgut fermentation may provide up to 30% of the total energy requirements, although in poultry this can be up to 8%
In the caeca, more than 90% of total SCFAs are constituted of several volatile fatty acids (VFA) as most know are acetic, valeric, propionic and butyric
Butyric acid it is the preferred energy source for the enterocytes and is known to regulate proliferation within the intestinal mucosa and cellular differentiation, thus increasing intestinal tissue weight

Question 6

Feed accounts for

Answer 6

approximately 70%

of the cost in intensive poultry production

Question 7

Feeding standards

Answer 7

• Feeding standards are statements of the food or nutrient requirements of animals, of different weights and types for different purposes, such as maintenance and the production of meat or eggs
• Poultry diets must be formulated to provide all of the bird’s nutrient requirements if optimum growth and production is to be achieved
• Dietary formulation for poultry - Poultry diets are composed primarily of a mixture of several feedstuffs such as cereal grains, soybean meal, animal by-product meals, fats, and vitamin and mineral premixes (information can be found in NRC 1994; breeder’s recommendations more appropriate)
• The most important factors in dietary formulation are: Metabolisable energy, Crude protein, Lysine, Methionine + Cysteine, Calcium, Available Phosphorous, Sodium

Question 8

Carbohydrates

Answer 8

– the major source of energy for poultry. Most of the carbohydrate in poultry diets is provided by cereal grains e.g. wheat

Question 9

Fats

Answer 9

provide energy and essential fatty acids that are required for some bodily processes

Question 10

Proteins

Answer 10

required for the synthesis of body tissue (particularly muscle), physiological molecules (such as enzymes and hormones), feathers and for egg production. Proteins also provide a small amount of energy

Question 11

Vitamins

Answer 11

organic chemicals (chemicals containing carbon) which help control body processes and are required in small amounts for normal health and growth

Question 12

Minerals

Answer 12

inorganic chemicals (chemicals not containing carbon) which help control body processes and are required for normal health and growth

Question 13

Factors affecting the nutrient requirements

Answer 13

Genetics - the species, breed or strain of bird – have different average body sizes, growth rates and production levels and will absorb and utilise nutrients from feed with different levels of efficiency. Therefore, they will require feed with different nutrient compositions. The genetics of commercial poultry is constantly changing, and as a result, so are their nutrient requirements. Consequently, breeders of commercial poultry provide information on the specific nutrient requirements for the birds they sell
• Age – nutrient requirements are related to both body weight and the stage of maturity in bird
• Sex – prior to sexual maturity, the sexes have only small differences in their nutrient requirements and males and females can usually be fed the same compromise diet to achieve acceptable growth rates. Differences in nutrient requirements are larger following the onset of sexual maturity and significantly different diet formulations are then required for each sex
• Reproductive state – the level of egg production in hens and sexual activity in males will affect nutrient requirements
• Ambient temperature – poultry have increased energy requirements to maintain normal body temperature in cold ambient temperatures and the opposite in hot ambient temperatures
• Housing system – the type of housing system will influence the level of activity of the birds and therefore their energy requirements.
• Health status – birds experiencing a disease challenge may benefit from an increase in the intake of some nutrients, most commonly vitamins.
• Production aims – the optimal nutrient composition of the diet will vary according to production aims, such as optimising weight gain or carcass composition, egg numbers or egg size. Poultry that are raised for breeding purposes may need to have their energy intake restricted to ensure that they do not become obese.

Question 14

Raw materials used in poultry feed

Answer 14

• Cereal and grains: maize, rice, wheat, sorghums, broken rice are the main energy source in diets
• Cakes or Oil meal: soybean meal, rapeseed meal, sesame meal, sunflower meal, groundnut cake, coconut meal, palm meal are used as protein sources
• Oils and fats: vegetable oils usually because there are some restrictions using animal fats energy source in diets
• Feed of animal origin: meat meal, fish meal, bone meal - Restrictions!!!
• By-products: rice bran, rice polish, solvent extracted rice, wheat bran
• The use of raw materials often depends on geographical location
  
  • Minerals and vitamins: poultry feeds are enriched with calcium, phosphorus, trace minerals such as Fe, Zn, Mn, Cu, CO and I and vitamins A, D3, E, K and B Complex. Usually in the form of premixes usually excluding Ca and P
• Feed additives: additives commonly used are antibiotics (usage not banned in India), prebiotics, probiotics, enzymes, mould inhibitors, toxin binders, anticoccidial supplements, acidifiers, amino acids, antioxidants, feed flavours, pigments and plant extracts
• Exogenous phytase and xylanase enzymes are incorporated in over 90% of the poultry diets produced world wide

Question 15

What is phytate …

Answer 15

Phosphorus (P) is an essential mineral for growing animals, and a lack of adequate supply of available P in diets may reduce performance and carcass quality, and increase mortality
Approximately 70% of plant P is organically-bound in a complex form, phytin - including phytic acid and phytates (salts of phytic acid), which is not available to pigs and poultry, because they do not produce sufficient amount of endogenous phytase
Phytate chelates divalent cations, react with protein and starch and reduce their bioavailability

Question 16

How to increase available P in diets ? Why we add phosphorus / phytase …

Answer 16

• Dietary supplementation with inorganic P
• Non-utilised phytate P still pollutes
• Dietary supplementation with phytase (myo-inositol hexaphosphate phosphohydrolases), enzyme that can hydrolyze the ester bonds between the phosphate groups and the inositol ring in phytates

Question 17

Gross energy

Answer 17

The quantity of heat resulting from the complete oxidation of unit weight of a food or excreta is known as the gross energy (GE) or heat of combustion of that food or excreta
The gross energy concentration of ether extract (fat) , protein and nitrogen-free extract (carbohydrates) is 39.2, 22.4, and 17.2 MJ/kg DM respectively
The cereals are rich in carbohydrates so most common foods for farm animals contain about 18.5 MJ/kg DM of gross energy. The gross energy of maize, wheat and barley is 18.4, 18.1 and 18.2 MJ/kg DM respectively

Question 18

Digestible energy

Answer 18

Not all of the gross energy of the foods is available and useful to poultry
After the process of digestion in the gastrointestinal tract most of the nutrients are absorbed by the animals. Digestion represents the physical and chemical processes which take place in the gastro- intestinal tract
This absorbed energy is termed digestible energy (DE). Small amount of undigested/unabsorbed nutrients is voided in the excreta
DE (MJ/kg) = [GE feed intake – (GE faeces)] / feed intake (kg)

Question 19

Metabolisable energy

Answer 19

Further losses of energy occur in the urine in the form of nitrogenous wastes and other compounds not oxidized by the animal body
The apparent metabolisable energy (AME) of the food is measured as a difference between the digestible energy and the energy of the urine
Metabolisable energy (ME) is a common measure of energy availability of poultry foods
ME (MJ/kg) = [GE feed intake – (GE faeces+GE urine)] / feed intake (kg)

Question 20

ME Correction for nitrogen retention

Answer 20

The ME of feed will vary according to whether the amino acids it supplies are retained by the birds for protein synthesis or are deaminated and their nitrogen excreted
For this reason, ME values are sometimes corrected to zero nitrogen balance, by deducting 34.39 kJ for each 1 gram of nitrogen retained

Question 21

Limits of ME system

Answer 21

The ME system does not account for intermediate metabolism
Different metabolised nutrients are utilised with different relative efficiencies for energy deposition (Kf=0.9, Kc=0.7, Kp=0.6 for fat, carbohydrate and protein respectively)
The actual values of these coefficients are normally lower than the theoretically predicted. The discrepancies are relatively small for fat deposition but much larger for protein deposition
However, differences in the amount of fats, carbohydrates and protein in the diets will affect the efficiency of ME utilization (energy retained) in the carcass
It also will affect the heat production, as feeding protein rich foods will increase
the heat increment of digestion

Question 22

Net energy

Answer 22

Theoretically, the best way of predicting feeding quality of feed for poultry is to use the net energy value of the feed
Net energy of the feed can be described as its ME corrected for the energy losses as a heat increment of digestion
The net energy of a food is that energy which is available to the birds for useful purposes. It can be also separate as net energy for maintenance (NEm) and net energy for production (NEp)
However, there is not a simple way to determine the NE in feed

Question 23

Crop

Answer 23

Chickens don’t have teeth, so they can’t chew food in their mouths. A chicken picks up food in her beak and swallows it with the help of her tongue. The food travels down the esophagus to the crop (which is really just a bulge in the esophagus), where the chicken stores the food until she can digest it at her leisure.

Question 24

Esophagus, stomach, and gizzard

Answer 24

The esophagus continues past the crop to the true stomach, the proventriculus, where digestion really gets rolling with the addition of hydrochloric acid and digestive enzymes. The food still hasn’t been chewed, though.

That happens a little farther down the line in the gizzard (also known as the ventriculus), which is another unique anatomical feature of birds. This muscular organ acts as the bird’s teeth to grind the food and mix it with digestive juices, with the help of several small stones that have been hanging out inside the gizzard, ever since the chicken ate them a while back.

Question 25

Digestive tract:

Answer 25

Chickens have a pancreas, liver, and intestines, which pretty much do the same things as they do in humans. The digestive tract layout differs, though, when you get to the cecum. The plural of cecum is ceca, which is useful to know, because birds have two. The ceca are blind pouches located where the small and large intestines come together.

Birds extract a little extra nutrition out of their meal, especially fatty acids and B vitamins, through the fermentation process that happens in the ceca.

Question 26

Kidneys and vent:

Answer 26

Chickens don’t pee, and they don’t have a bladder. Urinary system wastes (urates is the word used for bird urine) produced by the kidneys are simply dumped in with the digestive wastes at the end of the digestive system, at the cloaca, or vent. That’s why normal chicken droppings contain white urates mixed with darker digested material.