Illuminance and UV-A exposure during rearing affects egg production in broiler breeders transferred to open-sided adult housing.
1. Broiler breeders were reared in light-proof accommodation on 8-h photoperiods at an illuminance of 10 (W10), 40 (W40) or 100 lux (W100) from warm-white fluorescent lamps, or 10 lux (UV10) from Arcadia bird lamps (white light plus UV-A emission). At 20 weeks, 200 birds from each group were transferred to open-sided housing and a 16-h mixture of natural and warm-white fluorescent light. 2. Mortality during rearing and body weight at 20 weeks were similar for all groups. 3. The W10 birds matured 2 d later, had inferior rates of lay over peak production and laid 9 fewer eggs to 60 weeks than the other groups. Mean egg weight, extra large egg production and mortality between 20 and 60 weeks were unaffected by lighting during the rearing period. The UV10 birds had a significantly better rate of lay between 52 and 60 weeks than any of the groups reared on white light. 4. The findings suggest that ultraviolet radiation does not directly affect hypothalamic activity, but that retinally received UV during the rearing period prolongs the laying cycle through a modification of the hormonal control of photorefractoriness.
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Animal and Poultry Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa. northcot.7hg@dsl.pipex.com
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D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D052284:Clutch Size / Q000528:radiation effects; D005260:Female; D006799:Housing, Animal; D008027:Light; D009026:Mortality; D010063:Ovum / Q000254:growth & development / Q000528:radiation effects; D014466:Ultraviolet Rays