The effects of dietary protein levels, ahemeral light and dark cycles, and intermittent photoperiods on the performance of chicken broiler parent genotypes.
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.
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
D004044:Dietary Proteins