Effects of photostimulatory lighting and feed allocation in female broiler breeders 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 programs and two feeding programs. Pullets were individually caged in a light tight facility at 20 wk of age. The light period of fast photoperiod (FP) hens 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 increases 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 allocations 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 between 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 treatment. Whereas feeding program had no effect on carcass composition parameters at sexual maturity, the SP hens had a higher relative carcass lipid content at the expense of protein and ash content compared to FP hens. The weight of the large yellow ovarian follicles (LYF) at sexual maturity was affected 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 feeding programs using more rapidly increasing feed allocations.