High, Medium and Low Corn Silage Diets with and without Monensin for Feedlot Steers

Abstract

Ninety-six 612 lb (278 kg) steers were used to study the effects feedlot rations containing 14, 30 or 75% of their dry matter from corn silage (CS) with and without 300 mg per day monensin on feedlot performance and carcass merit. Monensin improved feed efficiency 6.0% across all roughage levels (P<.01) but had no effect on gain or carcass parameters. Feed intake of the monensin fed cattle was 5 to 14% lower than for the non-monensin fed cattle which is less than reported in other tests. Cattle receiving the 75% CS ration had 14% lower gains and were fed 28 days longer than cattle fed either 14 or 30% CS (196 vs 168 days). Carcass weights of the 75% CS cattle were 682 vs 713 lb (310 vs 324 kg) for the higher concentrate levels. The 75% silage cattle had lower (P<.01) dressing percents, lower marbling scores, lower percents of kidney heart and pelvic fat, and higher backfat thickness. While apparent live weight gain on the high CS ration was nearly as great 469 vs 477 lb (213 vs 217 kg) as the higher concentrate rations, final carcass weight was reduced by 22 to 37 lb (10 to 17 kg). Carcass grade was much lower on the higher CS cattle, but yield grades of cattle were comparable for all three groups. Dry feed per pound of carcass gain was increased as the level of silage increased in the ration. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.