The impacts of a fibrolytic enzyme additive on digestibility and performance in the grower period, and supplemental Saccharomyces cerevisiae on performance and rumen health in the finisher period for feedlot steers

Two experiments were conducted to determine the effects of a fibrolytic enzyme pretreatment on growth performance, apparent total tract digestibility, and ruminal pH throughout the grower and early finisher period (Exp. 1), and to examine the impact of Saccharomyces cerevisiae supplementation on intake, performance, and indicators of gut health in the late finisher period (Exp. 2). Fifty-four steers were randomly assigned to a subgroup determining experimental treatment groups. In Exp. 1, steers were randomized to: control (CON1; no enzyme) or enzyme (ENZ; 0.75 ml kg-1 DM of feed) dietary treatments. Digestibility was improved (P≤0.05) in ENZ steers for DM, CP, NEg, and sugars, but did not affect (P≥0.12) DMI, ADG, or reticulo-ruminal pH. In Exp. 2, the treatments were: control (CON2; no yeast) or yeast (YST; 3.0 g animal-1 daily) supplemented diets. Rumen papillae were collected for mRNA expression of gut barrier function (OCLN, CLDN, ZO1, ZO2) and immune response (TLR2, TLR4, FCAR) genes and histological measurements. YST decreased (PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author