Daily energy allotments and performance of broiler breeders. 1. Males.

The effects of daily energy intake on reproductive performance of Arbor Acres males and on growth of their offspring was studied. In Experiment 1, 21 males were placed in individual pens with 12 females. Three rations, differing in energy, were fed from 24 to 57 wk of age with seven males receiving either 300, 340, or 380 kcal ME/d. In Experiment 2, 32 individually caged males were given daily allotments of 280, 320, 360, or 360 kcal ME/d from 26 to 32 wk of age and 300, 340, 380, or 380 kcal ME/d from 32 to 38 wk. Rations of the two groups of males fed the highest energy level differed in formulation, one being the same wheat short-based basal ration as fed to the two lower energy groups, only with additional fat, and the other being a corn-soybean-based ration. Body weight and testes weight were increased with increased energy allotment in both experiments but carcass composition was unaltered. There were no significant effects of energy intake on fertility or hatchability in either experiment. Even though mean differences were not significant, fertility in two pens dropped to near zero at 38 wk in Experiment 1. Semen characteristics and plasma testosterone concentrations were unaffected by energy intake in Experiment 2. There was a significant linear increase in 6-wk BW of broilers associated with the increase in sire energy intake in each of three batches of broilers grown in Experiment 1 and in one of two batches of broilers grown in Experiment 2.