Intensive beef production from sorghum grain and sorghum stubble: Effects of methods of processing the grain and the stubble, vitamins A, E and K and selenium supplementation and anthelmintic treatment on rate and efficiency of body weight gain and carcass composition

Abstract

SUMMARYThe intensive finishing of steers on simple rations of 10% sorghum stubble and 90% sorghum grain plus urea was investigated. Fine grinding of the grain resulted in a lower mean daily intake, but a significantly greater efficiency of conversion of feed to carcass weight gain (P < 0·01) than coarse grinding the grain. Coarse chaffing of the stubble significantly reduced the intake of the stubble in comparison with hammer milling, but had no significant effect on rate of body weight gain, total feed intake or efficiency of feed conversion.The addition to the ration of either 1 mg of selenium, or 200 mg vitamin E, 200 mg vitamin E and 100 mg vitamin K per day had no significant effect on rate or efficiency of body or carcass weight gain. Seven out of 32 steers which were not injected with 3 million i.u. of vitamin A at the start of the experiment exhibited nyctalopia. None of the 32 steers which received the vitamin A injection had hepatic vitamin A concentrations less than 33 μg/g. Vitamin A injection did not have a significant effect on the rate of body weight gain (mean ±S.E. 1·3 ± 0·03 kg per day), efficiency of feed conversion (10·4 ± 0·16 kg D.M. per kg carcass weight gain), or time to attain slaughter weight (133 ± 3 days). Drenching twice with thiabendazole had no significant effect on rate of body weight gain.