Conclusion Future Objectives In Broiler Reproduction Management

The foregoing discussion leads to the main question: Can the growth requirement of broiler breeder hens be allied with good reproductive performance, good health, and welfare, either by a feed restriction program which does not cause undue hunger, or by innovative genetic selection? Several data in literature illustrate that growth and reproduction are mutually exclusive in selection goals, suggesting that there is a causal negative biological relation. If that is true, then one has to make choices in

Period 1 (1-6 weeks)

(16-age at first egg)

6

Delayed by restricted feeding

Age at first egg

Delayed by restricted feeding

Oviduct weight at age of first egg

Ovary weight at age of first egg

Multiple follicle sets at age offirst egg

No effect of feeding levels

Egg weight

Increases when fed ad libitum during this period

Increases when fed ad libitum during this period

Total and settable egg production

Increases when fed on restricted quantity during this period

Fig. 2 Schematic presentation of important periods during the rearing and prebreeding period in the determination of reproductive performance in broiler breeder females. (From Bruggeman, 1998.)

future broiler breeder management. The following choices are proposed.

1. Continue the intense selection of broilers, with the known consequences of the need for severe feed restriction of the breeders. This becomes difficult to defend when taking into account the animal welfare policy in some societies. In this case, it is feasible to develop new feeding regimens/diets more adapted to the animals' needs, thereby improving welfare in combination with acceptable egg production. This can possibly be achieved by diminishing the duration[2] or the intensity of feed restriction. Energy restriction can be realized by the introduction of diets with energy dilution. Whether these feeding strategies/diets have repercussions on egg production is hardly looked at.

but there will be a search for the optimal balance welfare/growth and reproduction goals.

2. Change selection goals in the broiler industry, thereby diminishing the need for severe feed restriction in breeders by selection, but without deterioration of the quality demands of the broiler. The introduction of new genetic lines of broiler breeder females that would tolerate ad libitum feeding could be a good alternative to counteract this welfare problem. The increasing production of slower-growing Label chickens (France), for example, has led to a practice of mating a heavy broiler cockerel with a slow-growing Label breeder hen. The resulting broiler reaches market weight 10-12 days later than a standard broiler. Another alternative is the dwarf broiler breeder hens, which seem to maintain a relatively good reproductive fitness even with ad libitum feed allowances during growth.[12'13] The presence of the dwarf gene (dw) suggests that its presence may reduce the need for feed restriction in the breeder while allowing the production of fast-growing offspring. However, one has to bear in mind that this divergent selection leads to an unnatural biological situation in which natural mating can become very difficult because of the extreme size differences between male and female. The production of broilers depends on artificial insemination in such cases, as in the turkey industry. It can be questioned, from an ethical point of view, if this might affect the integrity of the animal as a population.

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