Effects of supplemental amylase and roughage source on performance and carcass characteristics of finishing beef cattle

The use of enzymes in feedlot diets has not been evaluated extensively, and most research with high-concentrate diets has been with barley. Beauchemin et al. (1997) evaluated the addition of two enzyme mixtures that varied in the proportion of xylanase and cellulase activity to 95.1% concentrate feedlot diets based on either barley or corn. Feed efficiency for the overall finishing period was improved approximately 11% with a high-xylanase activity enzyme treatment of barley compared with untreated steam-rolled barley. With corn, however, the addition of the high-cellulase activity enzyme improved feed efficiency compared with no enzyme addition. Less research has been done with the addition of enzyme preparations that contain amylase to cattle diets. Hristov et al. (2000) dosed 0, 100, 200, or 400 g/d of an enzyme preparation that contained carboxymethylcellulase, xylanase, βglucanase, and amylase into the rumen of cannulated heifers fed an 85.5% rolled barley diet. Enzyme treatment linearly decreased ruminal pH and quadratically increased in situ effective degradability of the diet. Ruminal amylase activity was not increased by dosing the enzyme, but duodenal amylase activity increased quadratically with enzyme addition. J. M Tricarico (Alltech, Inc., Nicholasville, KY, unpublished data) dosed 0, 12, 24, or 36 g/d of an amylase preparation to 24 Holstein cows fed a corn silage-ground corn diet. The addition of 12 g/d of amylase increased 24-h ground corn digestibility, milk fat yield, and milk protein yield. Although these data suggest potentially positive effects on cattle performance with addition of enzymes to feedlot diets, performance results for enzyme preparations with high amylase activity are not available in the literature.