The response of male chicken broilers to the dietary addition of virginiamycin

Two replicate trials, each involving 400 Arbor Acre male broiler chicks, were conducted to determine the effect of virginiamycin as a growth promoter when added to either the feed or drinking water. A control group received no growth promoter while one treatment group was provided a diet containing 11 mg of virginiamycin/kg. Another treatment group was provided drinking water containing virginiamycin in amounts calculated to ensure equivalent or one-half equivalent intake of the antibiotic. Virginiamycin supplementation had no significant (P greater than .05) effect on mortality or feed conversion ratios, regardless of the mode of administration. Body weights at 21 days of age but not at 42 days of age were significantly (P less than .05) heavier for broilers receiving virginiamycin via the drinking water. The inclusion of virginiamycin in the feed failed to improve body weights at either 21 or 42 days of age.