The principle of the study was to assess the influence of yeast-fermented cassava pulp (YFCP) as a protein supplement on feed intake, nutrient digestibilities, rumen microbial protein synthesis, fermentation end-products, and N-balance in Thai native beef cattle. The experiment was conducted following the 4 × 4 Latin square design using 4 levels of YFCP supplementation (0, 100, 200, and 300 g/head/day) in 3-year-old Thai native beef cattle crossbreds. The response of YFCP supplementation level using rice straw as a roughage source revealed promising results. The rumen ecology parameters including cellulolytic, amylolytic, and proteolytic bacterial population were significantly increased while the protozoal population were reduced, as affected by increasing level of YFCP supplementation (P < 0.05). In parallel with these results, totals VFA, propionate (C3) production in the rumen, and the ratio of C2:C3 were remarkably increased (P < 0.01), while rumen methane production by prediction from VFA was decreased (P < 0.01), as YFCP supplementation increased. Regarding, the nutrient digestibilities, those of OM and CP were remarkably enhanced (P < 0.01), hence increased DM intake. Furthermore, the use of YFCP at high level resulted in the highest N-balance and N retention absorption (P < 0.01). The results indicated that YFCP can be nutritionally enhanced by yeast fermentation, thus is promising to be used as a protein source in ruminant feeding.
Keywords: Cassava pulp; Protein source; Ruminant feeding; Yeast-fermentation.