Growth Rate, Feed Conversion, and Dietary Metabolizable Energy in Response to Virginiamycin Supplementation of Different Diets

Virginiamycin at a dietary concentration of 22 ppm stimulated growth rate and improved efficiency of feed conversion in broilers fed different diets. The dietary variations were practical ones which would alter the milieu of the intestinal bacteria. They involved the use of wheat vs. corn as principal dietary cereal, different levels of fat, and different levels of protein. All the diets supported similar performance and there were no significant interactions in response between diet and antibiotic. Body weights at 53 days of age averaged 5% heavier in the virginiamycin-fed birds and the average rate of improvement in feed conversion efficiency was 5.4%. At 26 days respective values for the above were 10.3% and 9.5%. The energy metabolized from the diets was increased by 7.2% when the diets contained virginiamycin.