Carcass Composition and Production Criteria of Surgical Capons As Affected by Nutrition

Three strains of broiler type cockerels were used to evaluate capon rations. The three experiments involved different (1) protein levels, (2) energy levels and (3) feeding programs for surgically caponized birds. Among birds fed 14, 16, 18 and 20 percent protein, there was no significant difference in final weight, efficiency of feed utilization or muscle composition. The 14-percent group had a greater incidence of breast blisters. When diets with productive energy:protein ratios of 50:1, 55:1, 61:1 and 67:1 were fed, there was a significant increase in weight gains and efficiency of feed utilization, as the ratio increased. Also, as energy increased, moisture decreased in the breast and thigh muscles. Fat increased in the thigh muscle only, and protein was not affected. There was no consistent effect of energy level on the breast blister condition. The third trial, involving full-feeding, limit-feeding (manual and restricting caloric intake) and finishing diets, resulted in slightly better gain and efficiency with manual limit-feeding than with any of the other methods. This group did have the highest incidence of breast blisters, but the overall effect of these methods of feeding was inconsistent. It was concluded that 16 percent protein is adequate in capon rations after 6 weeks of age. An energy:protein ratio of at least 60:1 with a restricted feeding program was suggested by these trials. It also was concluded that diet or feeding program has little effect on the breast blister condition. In all three trials, mortality was not affected by any of the treatments.