Effects of various feeding regimens on reproduction in broiler-breeder males

A study was conducted using commercial broiler-breeder males and females maintained in all-litter pens allowed to mate naturally. Using a separate feeding arrangement, males were given a diet containing either 12% or 14% protein. Body weights were maintained at either 90% or 100% of the recommended level. Females were provided feeders with grills which denied males access to the feed, while male feeders were elevated 46 cm above the floor to deny female access to that feed. In control pens, males and females ate from the same feeders and received a breeder diet with 14% protein. Eggs produced in pens where the males and females were fed separated showed significantly higher fertility (4.2%) than eggs from control pens. No differences in percentage fertility were noted between the two dietary-protein levels or body-weight groups of males fed separately. Furthermore, no differences were measured in percentage hatch of fertile eggs among any of the treatment groups. Males in control pens showed significantly heavier body weights and breast-angle measurements starting at 32 and 40 wk of age, respectively. No treatment effect was measured for male pododermatitis. The male control birds had heavier testes weights than the males in the groups with restricted body weights. However, semen concentration was not affected. This indicates that the improved fertility was related to the size and weight of the males, not to their ability to produce semen. The reduced fertility associated with excess male body weight may be both physical and physiological in nature.