Resumo

LEWIS, P.D.  e  GOUS, R.M.. Broiler breeders should not be reared on long photoperiods. S. Afr. j. anim. sci. [online]. 2007, vol.37, n.4, pp.215-220. ISSN 2221-4062.

Sexual maturity is delayed and egg numbers are reduced when broiler breeders are reared on long photoperiods. However, this is the recommended procedure for rearing spring-hatched birds in non-lightproof buildings. Research at the University of KwaZulu-Natal has suggested that this advice may be incorrect, and that precocity is not a problem in control-fed broiler breeders reared on increasing daylengths. This trial compared the responses of four broiler breeder genotypes to a typical lighting programme advocated for birds in lightproof housing with the provision of 14-h photoperiods to 20 weeks and 16 h in lay. The long-day rearing resulted in a 26-d delay in sexual maturation, seven fewer eggs to 60 weeks, a 2.5-g increase in egg weight, less efficient feed conversion, heavier body weights at sexual maturity and throughout the laying period, and a higher incidence of mortality. It is concluded, therefore, that broiler breeders should not be reared on long photoperiods, even when hatched in the spring and kept in non-lightproof facilities, because of the adverse consequences of a delay in the dissipation of photorefractoriness.

Palavras-chave : Broiler breeder; light; rearing; long days; out-of-season.

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