The aim of this chapter is to describe the potential reproductive performance of individuals, such that the potential reproductive performance of a population of hens may be simulated. This requires an understanding of systems such as the attainment of sexual maturity in a flock of pullets and the physiological control of egg production in hens. The potential performance, that is, the number of eggs produced over the production cycle of a single laying hen is dependent on the age at which it becomes sexually mature, on its internal ovulatory cycle length and egg weight, and the rates at which these change over time, all of which are genetically determined and may be satisfactorily modelled. Using stochasticity, the potential laying performance of a flock may then be simulated from individual responses. While laying hens are usually given ad libitum access to feed, the daily food intake of broiler breeders is restricted. In both cases it is useful to be able to predict the amount of energy and of eachnutrient that is required to meet the maintenance and potential laying performance of each hen so that the voluntary intake of a feed of any given composition can be predicted, and the consequences on performance of food intake being constrained can be determined. It may not be economically justifiable to meet the requirements of the most demanding hens in a population: the economic optimum intake of nutrients would depend on the relative cost of feeding these birds and the revenue derived from the saleof the eggs they produce. The optimum daily nutrient intake must then be converted to a dietary concentration for feed formulation purposes, and to do this successfully voluntary food intake must be accurately predicted. If this can be done, such a model may then be used to optimize the way in which these different strains of laying hen should be fed so as to maximize profit for the enterprise.
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