Methane (CH₄) is an end-product of enteric fermentation in cattle

Yeast (Saccharomyces cerevisiae) has been used to improve the nutritive value of feedstuffs, especially rubber seed kernel. In the current study, rubber seed kernel was grated and subjected to solid-state fermentation with yeast to enhance the nutritive value. The yeast-fermented rubber seed kernel (YERSEK) was substituted for soybean meal in ruminant diets to evaluate the effect of YERSEK on feed intake, digestibility, rumen fermentation and microbial protein synthesis in dairy heifers. Five Holstein Friesian crossbred heifers with an initial body weight (BW) of 215 ± 20 kg were used in this research. The experimental design was a 5 × 5 Latin squared design and the dietary treatments were five levels of YERSEK at 0, 100, 150, 200 and 250 g/kg dry matter in concentrate at 1% of BW, with rice straw fed ad libitum. The supplementation with YERSEK reduced rice straw and total DM intake linearly (p < 0.05). The intake of neutral detergent fiber and acid detergent fiber decreased linearly (p < 0.05), while ether extract intake increased linearly (p < 0.01) with YERSEK supplementation. The ether extract digestibility tended to be high (p < 0.01) with increasing levels of YERSEK. Supplementation with the YERSEK did not change (p > 0.05) ruminal pH and blood urea nitrogen in this study, but ruminal ammonia nitrogen was increased (p < 0.01) in the heifers receiving YERSEK. Increasing the YERSEK levels did not adversely affect the proportion of volatile fatty acids (VFA), which included acetate, propionate and butyrate and the microbial population (p > 0.05). Microbial protein synthesis was similar among the treatments (p > 0.05). The inclusion of YERSEK at 250 g/kg DM in concentrate feed had no effect on the utilization of feed, rumen fermentation characteristics and microbial protein synthesis. The YERSEK could be used as a protein replacement for up to 86% of the soybean meal in feed concentrate for dairy heifers.

This experiment was conducted to assess the effect of hydrolyzed yeast (HY) on growth performance, nutrient digestibility, rumen fermentation, and hematology in growing crossbred Bos indicus cattle. Twenty crossbred beef cattle with an initial body weight (BW) of 142 ± 12 kg were randomly assigned to one of four treatments for 90 d in a randomized complete block design (RCBD) having five blocks based on a homogenous subpopulation of sex and BW. Cattle were fed with a total mixed ration (TMR) and supplemented with HY at 0, 1, 2, and 3 g/kg dry matter (DM), respectively. Supplementation with the HY did not change average daily gain (ADG), dry matter intake (DMI), and gain to feed ratio (G:F) (p ≥ 0.06). The addition of HY did not adversely affect nutrient intake (p ≥ 0.48), while the digestibility of crude protein (CP) increased quadratically (p= 0.03) in the cattle receiving HY. The addition of HY did not affect rumen pH, but NH₃-N concentration increased linearly (p = 0.02) in the cattle. The total volatile fatty acid (total VFA) increased quadratically (p= 0.03) when cattle were fed with HY supplementation. The proportion of acetate decreased cubically (p= 0.03) while propionate increased cubically (p= 0.01), resulting in a decrease in the acetate to propionate ratio (p= 0.01) when cattle were fed with HY supplementation. In addition, acetate was the lowest, but total VFA and propionate were the highest in cattle fed the HY at 2 g/kg DM. Butyrate increased cubically (p = 0.02) with the addition of HY. The protozoal and fungal populations were similar among treatments (p ≥ 0.11), but the bacterial population increased linearly (p < 0.01) with the addition of HY. Supplementation of HY did not influence blood urea nitrogen (BUN), red blood cells (RBC), hemoglobin, hematocrit, white blood cells (WBC), lymphocytes, or eosinophils (p≥ 0.10). However, monocytes and neutrophils increased linearly (p = 0.04 and p = 0.01, respectively) by HY supplementation. In conclusion, supplementation of HY at 2 g/kg DM promotes CP digestibility, rumen fermentation efficiency, and hematology but does not affect the growth performance of growing beef cattle.

The purpose of this study was to determine how ruminal Crabtree-negative yeast affects the nutritional characteristics of winged bean (Psophocarpus tetragonolobus) tubers (WBT), in vitro gas and digestibility, and rumen fermentation. The experiment was carried out in a randomized complete design with a 5 × 2 (+1) factorial arrangement. Factor A determined the WBT products (a₁ = dry WBT, a₂ = fermented WBT without yeast in media solution, a₃ = fermented WBT with Pichia kudriavzevii KKU20, a₄ = fermented WBT with Candida tropicalis KKU20, and a₅ = fermented WBT with Saccharomyces cerevisiae), whereas factor B determined the level of fermented WBT replacing cassava chips (b₁ = WBT at 50% and b₂ = 100% levels). The results of the experiment showed that the fermentation approach could increase the crude protein (CP) content of WBT by around 7% (p < 0.01). The WBT fermented with yeast lowered the number of aerobic bacteria during the fermentation process (p < 0.01). P. kudriazevii KKU20 yeast strain had a 17.3% higher final asymptotic gas volume (Vf) than the C. tropicalis KKU20. Crabtree-negative yeast had a higher in vitro dry matter digestibility (IVDMD) than Crabtree-positive yeast after 12 h of incubation (p < 0.01). Fermented WBT with yeast had a higher IVDMD after 24 h of incubation than fermented WBT without yeast in the media solution (p < 0.05). The fermented WBT with C. tropicalis KKU20 enhanced propionic acid (C3) concentrations when cassava chips were replaced for half of all of the diet (C3 ranged from 26.0 to 26.4 mol/100 mol; p < 0.01). Furthermore, Crabtree-negative yeast isolated from the rumen stimulates rumen bacteria more effectively than Crabtree-positive yeast (p < 0.01). According to our findings, nutritional enrichment with yeast might increase the in vitro gas production and digestibility of WBT. The study also demonstrated that Crabtree-negative yeast has a promising lead in terms of improving rumen fermentation quality. However, further research is required before deciding on an effective approach for optimizing the potential of WBT as a feed source.

The goal of this study was to improve the nutritional value of cassava peel by using yeast (Saccharomyces cerevisiae) or effective microorganisms (EM), then use it as a replacement for concentrate, and examine the effects on the feed intake, feed digestibility, rumen fermentation, and growth performance of goats. The experimental design was a randomized complete block design (RCBD), and the dietary treatments were (1) concentrate, (2) replacement of the concentrate by yeast-fermented cassava peel (YFCP) at 50% and (3) replacement of the concentrate by EM-fermented cassava peel (EMFCP) at 50%. Twelve goats were given concentrate based on their treatments at a rate of 1.5% of their body weight. Rice straw was used as roughage and fed freely. It was found that the crude protein (CP) content of the cassava peel from 2.1% to 13.7–13.8% after 14 days of fermentation. Moreover, there were no significant differences between the treatments in terms of the feed intake, feed digestibility, ruminal pH, blood urea nitrogen concentration, volatile fatty acid profile, overall average daily gain, and feed efficiency. However, the cost of the feed per gain decreased when the YFCP or EMFCP was used instead of the concentrate. Based on the results of this experiment, it was possible to conclude that yeast or EM might be utilized as microorganisms to increase the nutritional value of cassava peel. Moreover, YFCP or EMFCP can replace concentrate by up to 50% without an impact on the feed intake, feed digestibility, rumen fermentation characteristics, and the growth performance; whereas, it can reduce the feed cost per gain up to 32%.