The intake of nutrients is a function of the amount of feed eaten and the nutrient levels in the diet.
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 modern brown-egg laying hens in relation to target body weight. From Week 18, hens start to enter their laying period, reaching peak of lay around 32 weeks of age, and typically maitaining egg production until 65-68 weeks of age. Feed intake will increase to a steady level of 100-105g per day and hen body weight will reach a mature level of 1700-1800g.
Table 1. Body weights and associated feed consumption for a brown-egg laying breed during the growing period
Chicks require a diet that can provide the nutrients needed for rapid growth and feather development. Chicks are given relatively high levels of energy, protein and the vitamins and minerals for the starter period. Once the chicks are fully feathered their energy requirements are reduced. Feeding management for layer pullets aims to maintain a growth rate that will lead to the pullet reaching sexual maturity at the desired age while avoiding obesity. The stage at which a pullet will start laying eggs is affected by age, bodyweight and day length.
On a percentage basis, layer pullet diets have lower energy and protein levels than chick diets. Different breeders recommend different feeding strategies for their birds, including the number of different diets fed during the pullet growing stage. Many breeders recommend a pre-lay diet that increases some of the nutrient levels, such as calcium, that will be required by the bird when it begins to lay eggs. Table 2 provides data on typical nutrient levels for layer diets for the growing period.
Table 2. Growing period nutrition recommendations
|Product Age in Weeks||Starter 0-6||Grower 6-12||Developer 12-15||Pre-Layer15-1 %Production|
|Methionine + Cystine||%||Min||0.82||0.71||0.58||0.65|
The aim of layer diets is to optimise egg production, provide the nutrition required to safeguard health and maintain the desired bodyweight. This can be in terms of egg numbers, egg size or egg mass. As with layer pullets, different breeders recommend different feeding strategies for their birds, including the number of different diets fed during the laying stage. Calcium is increased in the ration for egg shell formation. Table 3 provides data on typical nutrient levels for layer diets.
Table 3. Examples of layer diets (at 100g per day intake level)
|Nutrients||Units||1%-32 weeks||32-44 weeks||44-55 weeks||55 weeks and beyond|
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