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

• Published in: Canadian journal of animal science Vol. 101; no. 3; pp. 527 - 547
• Main Authors: Williams, Melissa S., AlZahal, Ousama, Mandell, Ira B., McBride, Brian W., Wood, Katharine M.
• Format: Journal Article
• Language: English
• Published: Ottawa Canadian Science Publishing 01-09-2021; NRC Research Press; Canadian Science Publishing NRC Research Press
• Subjects: additifs alimentaires; beef; bœuf; Cattle; Conversion ratio; Costs (Law); Diet; Digestibility; Dry matter; enzyme fibrolytique; Enzymes; Farmers; Feed additives; Feed conversion; Feed efficiency; Feedlots; fibrolytic enzyme; Gene expression; Histology; Immune response; Immune system; levure; Nutrients; Papillae; pH effects; Physical growth; Proteins; RNA; Rumen; Saccharomyces cerevisiae; Subgroups; Sugar; TLR2 protein; TLR4 protein; Toll-like receptors; Yeast; Yeasts; Canada; United Kingdom
• ISSN: 0008-3984; 1918-1825
• DOI: 10.1139/cjas-2020-0134

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). A total of 54 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 dry matter (DM) of feed] dietary treatments. Digestibility was improved (P ≤ 0.05) in ENZ steers for DM, crude protein, net energy for gain, and sugars but did not affect (P ≥ 0.12) dry matter intake (DMI), average daily gain (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, and ZO2) and immune response (TLR2, TLR4, and FCAR) genes and histological measurements. Yeast supplementation decreased (P < 0.001) DMI by 31%, reduced variation in DMI, and improved feed conversion ratios but did not impact rumen health mRNA expression or histology measures (P ≥ 0.07). Overall, enzyme supplementation improved the digestibility of some nutrients in the grower period, and yeast supplementation improved feed efficiency, without impacting growth performance or gut health.