Various photoperiods and Biomittent lighting during rearing for broiler breeders subsequently transferred to open-sided housing at 20 weeks.
1. Cobb broiler breeders were fed to achieve typical body weight targets (2.1 kg at 20 weeks) on 6-, 8-, 10- or 16-h fully or intermittently illuminated (Biomittent) photoperiods in controlled-environment housing to 20 weeks, then moved to open-sided housing and 16-h photoperiods to 60 weeks. 2. At each photoperiod, birds given Biomittent lighting had heavier body weights up to 42 d, lighter body weights between 49 and 140 d, but similar body weights at sexual maturity. 3. Irrespective of lighting type, birds given 8-h photoperiods matured 3 to 4 d earlier than 6- or 10-h birds, but all matured=15 d before 16-h birds. 4. There were no significant differences between the 6-, 8- or 10-h groups for total eggs, mean egg weight or egg mass output, but all three produced=13 more, but =0.5 g smaller, eggs and =0.83 kg more egg mass to 60 weeks than 16-h birds. The proportion of abnormally large eggs was low (0.73/bird) and similar for all lighting groups. Egg production for a given period after sexual maturity was similar for all groups, and so differences among groups could be explained by the differences in age at sexual maturity.
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Animal and Poultry Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa. peter.lewis@dsl.pipex.com
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D000375:Aging; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000254:growth & development*; D005260:Female; D006799:Housing, Animal; D008029:Lighting; D010058:Oviposition; D010063:Ovum; D017440:Photoperiod; D012741:Sexual Maturation