Nutrient digestibility and ruminal parameters of cattle fed dried brewers grains and Saccharomyces cerevisiae

Abstract

The objective of this study was to evaluate the effect of Saccharomyces cerevisiae on nutrient intake and digestibility, the protozoan population and ruminal fermentation kinetics of cattle fed diets containing brewers grains. Four ruminally cannulated crossbreed steers were distributed in a 4 × 4 Latin square. The treatments were in a 2 × 2 factorial arrangement: with or without the inclusion of brewers grains x with or without the addition of S. cerevisiae. Dried brewers grains were included at 11.7% of the dry matter (DM) of the diet. Yeast (S. cerevisiae CNCM I-1077 containing 1.0 × 109 CFU/g) was supplied at 15 g/day. The use of brewers grains and the addition of yeast did not influence the ingestion of DM, crude protein, neutral detergent fiber or total digestible nutrients. Steers fed with brewers grains ingested lower concentrations of non-fibrous carbohydrates (NFC) (P < 0.01). The addition of yeast did not alter DM or nutrient digestibility, but the inclusion of brewers grains reduced DM (P < 0.05) and NFC digestibility (P < 0.01). The use of brewers grains reduced the protozoa populations of the genera Entodinium (P < 0.05) and Isotricha (P < 0.01). Ruminal pH values were not influenced by brewers grains or yeast. There was an interaction between time and the inclusion of brewers grains (P < 0.05) for ammoniacal nitrogen, wherein two hours after feeding, cattle that consumed this by-product had lower concentrations of ammoniacal nitrogen, compared to those that did not consume brewers grains. The addition of live yeast did not influence the proportion of volatile fatty acids (VFA) or total VFA concentration, but the inclusion of brewers grains reduced the VFA concentration and the percentage of isovalerate (P < 0.05). Thus, the use of S. cerevisiae in the bovine diet did not improve fiber digestibility or ruminal fermentation parameters, and the inclusion of 11.7% dried brewers grains did not compromise the total digestible nutrient intake, ruminal pH or the concentrations of acetate, propionate and butyrate.