Broiler breeders should not be reared on long photoperiods

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.