Influence of virginiamycin and dietary manganese on performance, manganese utilization, and intestinal tract weight of broilers.

An experiment was conducted with day-old Cobb feather-sexed chicks for 21 days to study the effect of virginiamycin and dietary manganese on tissue uptake of manganese and intestinal tract weight. The 2 X 2 factorial arrangement of dietary treatments included 0 or 12 ppm virginiamycin and 0 or 1000 ppm added manganese as MnSO4 X H2O. Ad libitum intake was determined with four pens of five birds fed the basal corn-soybean meal diet. To eliminate the possibility that tissue manganese concentration of virginiamycin-fed birds could be attributed to increased dietary manganese intake, chicks fed experimental diets were restricted to 90% of the previous day's intake of ad libitum-fed birds. Feed intake, average daily gain, and feed efficiency were not affected by treatments. Virginiamycin decreased (P less than .001) relative intestinal tract weight from 3.34 to 2.68 g/100 g body weight. Kidney and bone manganese increased (P less than .05) when virginiamycin was fed (14.0 vs. 15.4 ppm dry basis and 21.8 vs. 24.6 ppm ash basis, respectively), indicating that virginiamycin increased absorption of manganese.