Broiler breeders feeding

Poultry diets must be formulated to provide all of the bird’s nutrient requirements if optimum growth and production is to be achieved. There are six classes of nutrients:

·        Carbohydrates – the major source of energy for poultry. Most of the carbohydrate in poultry diets is provided by cereal grains.

·        Fats – provide energy and essential fatty acids that are required for some body processes.

·        Proteins – 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.

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

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

·        Water.

Factors affecting the nutrient requirements of poultry

The nutrient requirements of poultry are affected by a large number of factors, including:

Genetics (the species, breed or strain of bird)

Red jungle fowl

Different species, breeds or strains of bird have different average body sizes, growth rates and production levels and will also absorb and utilise nutrients from feed with different levels of efficiency, leading to different nutrient requirements. As the genetics of commercial poultry is constantly changing 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.

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. The process of digestion of food produces body heat and the amount of heat produced will vary according to the nutrient composition of the diet. This is called the heat increment of the diet. In cold temperatures it may be desirable to formulate a diet with a higher heat increment and the opposite in hot temperatures.

Free range laying hens

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

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.

Nutrient requirements of egg laying chickens

Broiler chickens

The intake of nutrients is a function of the amount of feed eaten and the nutrient levels in the diet.

Feed consumption

There are a number of factors that influence voluntary feed intake. These are discussed in the Section on Feed intake. Table 1 provides data on typical feed consumption for brown-egg laying hens in relation to body weight.

Table 1. Body weights and associated feed consumption for a brown-egg laying breed

Source: Commercial layer management training course

Nutrient levels for layer chick diets

Chicks require a diet that can provide the nutrients needed for rapid growth and feather development. Chick diets (often called starter diets) are relatively high in energy, protein and the vitamins and minerals required for growth and development. Table 2 provides data on typical nutrient levels for layer chick diets.

Table 2. Examples of layer chick diets

Selected nutrients	1-diet starter	2-diet starter
	Chick starter (0-5 weeks)	Chick super starter (0-3 weeks)	Chick starter (3-9 weeks)
ME (MJ/kg)	11.7	12.3	11.9
Crude protein (%)	19.5	21.0	19.0
Lysine (%)	0.96	1.20	1.00
Methionine (%)	0.39	0.50	0.43
Linoleic acid (%)	1.00	1.10	1.10
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