title: The effects of dietary protein levels, ahemeral light and dark cycles, and intermittent photoperiods on the performance of chicken broiler parent genotypes.
abstract: Two experiments were undertaken to estimate the effect of: 1) two dietary protein levels (13.6 and 15.4%) in breeder diets fed to commercial meat parent genotypes; and 2) 6 photoperiods involving both 24-hr and 27-hr (ahemeral) day cycles with single stage and intermittent lighting for birds housed in floor pens. It was concluded that the 13.6% protein breeder diet, which provided from 14.8 to 20.9 g of protein per bird per day and from 301 to 425 kcal of ME per bird per day, was adequate to support optimum performance. The ahemeral light treatment 14L:13D used from 168 to 448 days had a depressing effect on egg production and feed efficiency compared with the conventional 24-hr day cycle with 14L:10D light treatment. The 14L:13D treatment, however, did result in increased egg size and improved shell strength. The intermittent light treatments, whether ahemeral or 24-hr cycle, resulted in improved egg weight and shell strength. The ahemeral intermittent treatment (10L:12D:2L:3D) had the effect of depressing fertility and hatchability, whereas the 24-hr intermittent photoperiod (10L:9D:2L:3D) resulted in fertility and hatchability equal to or better than other treatment. It was concluded that the 24-hr intermittent light treatment (10L:9D:2L:3D) supported performance which was equal to or better than other light treatments including the 27-hr ahemeral day cycles. Furthermore, ahemeral day cycles resulted in large numbers of eggs laid on the floor (Ca. 50%. First and second order interactions appeared to be of minor importance.
mesh_terms: D000818:Animals; D002645:Chickens / Q000378:metabolism / Q000502:physiology*; D002940:Circadian Rhythm; D003624:Darkness; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D005838:Genotype; D008029:Lighting; D008297:Male
chemical_list: D004044:Dietary Proteins