Effect of post-fermentative yeast biomass as a substitute for soybean meal on feed utilization and rumen ecology in Thai native beef cattle

Abstract

The aim of this experiment was to study the influence of substituting soybean meal (SBM) with post-fermentative yeast biomass (post-FYeB) powder on feed intake, ruminal fermentation, and bacteria and protozoa content in rumen fluid in beef cattle. The study was conducted on four male Thai native beef cattle at around 1 to 2 years of age with an initial body weight (BW) of 120 ± 20 kg. The experimental design was a 4 × 4 Latin square design and the dietary treatments included four levels of SBM substitution with post-FYeB in concentrate feed: 0, 33, 67 and 100%. The used post-FYeB contained 26.4% crude protein. Increasing levels of post-FYeB in concentrate diets did not alter roughage intake and total intake (P > 0.05). Rice straw intake ranged from 2.0 to 2.1 kg DM/day while total intake ranged from 2.7 to 2.8 kg DM/day. Ruminal pH and temperature in cattle fed various levels of post-FYeB were not significantly different among treatments. Total volatile fatty acids (VFA) and VFA profiles were not altered by different levels of post-FYeB. Post-FYeB addition into diet did not change bacteria and protozoal populations (P > 0.05). Thus, the inclusion of post-FYeB as a replacement of SBM in ruminant diets up to 100% is suggested.