Yeast (Saccharomyces cerevisiae) as a Feed Additive for Feedlot Cattle

M.S. Williams1, O. AlZahal2, I.B. Mandell1, B.W. McBride1, G.B. Penner3, M. Steele1, and K.M. Wood1
1 Department of Animal Biosciences, University of Guelph, Guelph, ON
2 AlZahal Innovation & Nutrition, Kitchener, ON
3 College of Agriculture and Bioresources, University of Saskatoon, Saskatoon, ON


ANAC Scholarship Recipient

Feed additives are derived from many origins and have been used in the animal production industry with increased use in the last three decades due to positive impacts on animal health and performance. With changing consumer demands and concerns of antimicrobial resistance, legislation limited access to in-feed antimicrobials in Canada as of December 2018. This has further increased the interest in other feed additives to improve animal growth, health, and efficiency. Yeast is a natural feed additive available in many forms, strains, and doses for livestock production; however, the majority of research in Saccharomyces cerevisiae yeast supplementation in livestock has focused on dairy cattle. Although modes of action have been proposed, one of particular interest for feedlot cattle is the ability to stabilize ruminal pH. It is postulated that S. cerevisiae aids in reducing lactate accumulation in the rumen by stimulating the production of lactic acid utilizing bacteria, ultimately increasing rumen pH (Chaucheyras-Durand et al., 2008). For feedlot cattle, the late finishing phase is that of greatest risk for ruminal acidosis and subsequent liver abscess, and poor animal performance (Nagaraja and Chengappa, 1998; Castillo-Lopez et al., 2014). Research was conducted on late finishing feedlot cattle that were supplemented with S. cerevisiae (60 billion colony forming units; YST) and compared to those that were not supplemented (CON) to evaluate growth performance, carcass characteristics, and indicators of rumen health (Williams et al., 2021). The results of that experiment suggested that YST decreased dry matter intake by 31% (P < 0.001) and improved feed conversion (P < 0.001) without impacting carcass characteristics or rumen health (P ≥ 0.07). Although this trial improved feed efficiency, the mechanisms of action of yeast for beef cattle remain unclear. Our future research program aims to increase the understanding of the modes of action of yeast as a direct-fed microbial in high-grain finishing feedlot cattle diets for the improvement of animal performance and health.

Keywords: yeast, saccharomyces cerevisiae, feedlot, beef