Roles of body weight and feed intake in ovarian follicular dynamics in broiler breeders at the onset of lay and after a forced molt.

Three experiments were conducted to define the relationships between BW and feed intake in broiler breeder female chickens at the onset of lay and after a forced molt. In experiment 1A the number of normal yellow follicles at the onset of lay and abdominal fatness were linearly related to BW, whereas age at first egg decreased with increasing BW in a curvilinear manner. Dietary energy was shown to be the limiting factor determining the onset of lay in severely feed restricted broiler breeders in experiment 1B. The source of energy (fat or carbohydrate) did not affect the onset of lay or ovarian function. In experiment 2 birds were feed restricted or fed ad libitum to 60 wk of age and force molted. Eight weeks after the initiation of molting, restricted birds were fed to 3 or 4 kg, and the birds fed ad libitum were fed to 4 or 5 kg of BW. After photostimulation the birds were fed ad libitum or 115 g/d. Taken together, the results of these analyses suggest that rearing treatment did not affect ovarian function, postmolt. Postmolt feed restriction was associated with lower follicle numbers compared with the groups fed ad libitum and was significantly lower in the lighter (3 kg) restricted birds compared with the other groups. Follicle numbers were lower after molting than at the onset of lay, and the effects of feed restriction were commensurately smaller.