Effect of feed allowance during rearing and breeding on female broiler breeders. 3. Ovarian steroidogenesis.

The influence of feed allowance during rearing (4 to 18 wk) and breeding (18 to 62 wk) on in vitro follicular steroidogenesis was examined. Four feeding programs were imposed: FF, consumed feed ad libitum throughout; FR, provided ad libitum access from 0 to 18 wk of age and restricted thereafter; RF, provided ad libitum access to feed from 0 to 4 wk, restricted from 4 to 18 wk, and consumed feed ad libitum thereafter; RR, consumed feed ad libitum from 0 to 4 wk of age and restricted thereafter. All birds received a starter diet (2,739 kcal ME/kg, 19.1% CP) from 0 to 3 wk of age, a grower diet (2,729 kcal ME/kg, 15.5% CP) from 3 to 22 wk of age, and a layer diet (2,889 kcal ME/kg, 14.6% CP) from 22 to 62 wk of age. Restricted feeding was based on commercial guidelines. At 33 wk of age, 10 to 12 (FF = 10, FR = 12, RF = 10, and RR = 11) birds from each feeding regimen were killed by cervical dislocation and the follicles removed for in vitro steroidogenesis. Feed allowance during breeding (18 to 62 wk) had a significant effect on in vitro follicular steroidogenesis at 33 wk of age. In broiler breeders fed ad libitum, some of the F2 (second largest) follicles had an endocrine profile characteristic of the F1 (largest) preovulatory follicles, secreting very little androstenedione and large amounts of progesterone. In feed-restricted birds, only the F1 follicles, which were destined to ovulate next, secreted any significant amount of progesterone into the culture media. Compared with restricted feeding, ad libitum feeding significantly increased the production of androstenedione in small white follicles (less than 1 mm).(ABSTRACT TRUNCATED AT 250 WORDS)