Influence of Virginiamycin on yield of broilers fed four levels of energy.

An experiment was conducted to determine the effect of dietary Virginiamycin on processing yields of broilers fed four levels of energy. Body weights (catch, slaughter) and carcass weights (dry shell and ready-to-cook) were recorded. Shrink (holding weight loss), water uptake, shell yield, and ready-to-cook yield of the carcasses were calculated. Body weights were higher at higher energy levels and with addition of Virginiamycin to the diets. Weight loss due to shrink declined from 5.39 to 3.89% at higher dietary energy levels, but shrink was not affected by Virginiamycin. Water uptake was significantly higher for carcasses of birds fed the lowest dietary energy level (3.49%) than for carcasses of birds fed the two highest energy levels (2.89 and 3.03%); but differences among water uptake of carcasses of birds fed the three highest energy levels were not significant. Water uptake was unaffected by Virginiamycin. Increasing the dietary energy level resulted in higher ready-to-cook yields, from 61.7% yield at 2,271 kcal ME/kg to 65.4% yield at 2,953 kcal ME/kg. Yield was increased from 63.3 to 64.0% (P less than .01) by dietary Virginiamycin.