An enzyme-microbial feed product for finishing steers.

B.A. Weichenthal*, LG. Rush, and B.G. Van Pelt,
University of Nebraska, Scottsbluff.

In a 119 d, 1995 trial reported at the 1996 Midwest ASAS meeting, the feeding of MSE, an enzyme-microhial product containing multiple enzymes plus bacteria, yeast and fungi, significantly improved daily gain and feed conversion over Rumensin-Tylan (R-T) fed to finishing, medium-framed, British crossbred yearling steers. This comparison was repeated in a 139 d, 1996 trial with large-framed, Charolais crossbred yearling steers, using similar diet dry matter composition that included 82.5% corn, 10% corn silage and 7.45% protein-mineralvitamin supplement. Calculated nutrient contents of the diet dry matter were 12.5% crude protein, 1.43 Mcal NEg per kg, .77% calcium and .34% phosphorus. The objective was to see if cattle performance and carcass results with MSE compared favorably with R-T. The MSE was added at feed mixing in a 20:80 premix with finely ground corn to include 1 kg of MSE per metric ton of diet dry matter. Rumensin and Tylan levels were 32 and 1 1 g per metric ton, respectively. Although numerical treatment differences in the 1996 trial were not statistically significant, pooled results for both trials resulted in means for final weight (adjusted to a 62% carcass dress), hot carcass weight, daily gain, feed conversion and dressing percent that were significantly improved for MSE (P at or < .l ). The mechanism for this response from a multiple component, enzyme-microbial product remains to be defined, but improved feed utilization is Suggested. Other means for carcass measurements were similar. Abscessed livers in the 1996 trial totaled 13.2 and 11.3% for R-T and MSE, respectively, and there was only one in 1995. ;key; Enzyme-microbial, Rutnensin-Tylan, Finishing

;table; Rumensin-Tylan (R-T) vs MSE for finishing yearling steers