Effects of photostimulatory lighting and feed allocation in female broilerbreeders 1. Reproductive development

Changes in carcass traits during sexual maturation were studied with female Shaver Starbro breeders in a 2 x 2 factorial design with two lighting prog rams and two feeding programs. Pullets were individually caged in a light t ight facility at 20 wk of age. The light period of fast photoperiod (FP) he ns was changed from 8L: 16D to 15L:9D at 20 wk of age. Slow photoperiod (SP ) hens were switched from a 8L:16D photoperiod at 20 wk to 11L:13D, with in creases to 12L: 12D, 13L: 11D, 14L:10D, and 15L:9D weekly to 24 wk of age. Slow feed (SF) hens were given small (5 g or less) weekly increases in feed allocation from 20 to 25 wk Fast feed (FF) hens received larger feed alloc ations than the SF birds from 20 to 25 wk (maximum difference of 25 g more feed than SF hens received). Birds were processed at weekly intervals betwe en 20 and 26 wk of age (Group A) or at sexual maturity (Group B), which was considered to be the day of the first oviposition. Age at sexual maturity did not differ due to photostimulation or feeding tr eatment. Whereas feeding program had no effect on carcass composition param eters at sexual maturity, the SP hens had a higher relative carcass lipid c ontent at the expense of protein and ash content compared to FP hens. The w eight of the large yellow ovarian follicles (LYF) at sexual maturity was af fected by feeding regimen (FF, 50.2 g; SF, 43.6 g) and photoperiod (FP, 43. 2 g; SP, 50.6 g). While hens on the SP photostimulation program had 8.9 LYF compared to 8.0 in FP hens at sexual maturity, the FF feeding regimen hens had 9.0 LYF compared to 7.9 in SF hens. The gradual feeding program of the SF treatment may be a potential means of limiting follicle recruitment and thereby potentially increasing settable egg production compared with feedi ng programs using more rapidly increasing feed allocations.