The response of growing and finishing cattle to Virginiamycin

Virginiamycin, discovered and manufactured in Belgium (De Somer, 1955) from a naturally occuring mould, is a steptogramin type antibiotic (Cocito, 1979). Steptomyces virginiae produces two antibiotic factors, M and S. Factor M is a cyclic lactone and is present as 60-70 per cent of Virginiamycin. It has been demonstrated that there is a synergism between these two factors (Chabbert, 1971) whose combined activity is three or more times that of the individual components. The mode of action in monogastric animals has been well documented in pigs (Henderickx, 1979) and this work has lead to recorded data on the influence of Virginiamycin on the absorption Of nutrients by these animals (Dierick, 1980). The advantages of supplementing broiler, layer, turkey and pig feeds with Virginiamycin have been recorded (Barber 1978, Krider 1978, Pellura 1980, Leibetseder 1980, Harnisch, 1980, Canale 1980, Korthas 1979 and Phillip, 1978). The producers of veal and beef calves have also used Virginiamycin and shown improved daily gain and feed conversion (Parigi-Bini, 1979). These data promoted the trials in growing cattle detailed in this paper.