Influence of increasing doses of a yeast hydrolyzate obtained from sugarcane processing on in vitro rumen fermentation of two different diets and bacterial diversity in batch cultures and Rusitec fermenters

Abstract

Live yeast cultures and yeast hydrolyzates can be used as rumen fermentation modifiers, but their effects and mode of action are different. Whereas the effects of live yeast cultures on rumen fermentation are well documented, yeast hydrolyzates have received much less attention. The influence of a yeast hydrolyzate from Saccharomyces cerevisiae, obtained after ethanol production from sugarcane (YHS), on in vitro rumen fermentation was investigated using both batch cultures and Rusitec fermenters inoculated with ruminal fluid from sheep. Batch cultures (300 mg dry matter (DM)) with two mixed diets (AHC, 0.5:0.5 alfalfa hayxoncentrate; BSC, 0.15:0.85 barley strawxoncentrate) as substrate were supplemented with increasing doses of YHS (0, 3.3, 6.7, 10.0 and 13.3 ml/1) and incubated for 16.5 h at 39 °C. Supplementation of increasing amounts of YHS to AHC-cultures increased (P < 0.05) linearly total volatile fatty acid (VFA) production and butyrate molar proportion, and decreased (P < 0.001) acetate proportion and acetate:propionate ratio. In contrast, only subtle effects of YHS on NH 3-N concentrations and molar proportions of isovalerate and caproate were observed for the BSC diet. Longer-term effects of YHS supplementation on rumen fermentation of AHC diet were investigated using four Rusitec fermenters in a cross-over experimental design with two 14-day incubation periods. Fermenters were given daily 30 g of diet DM, and in each period half of them were supplemented daily with 5 ml of YHS (10.0 ml/1) Supplementing with YHS did not affect (P > 0.05) total VFA production, lactate concentrations, DM and aNDFom disappearance or enzymatic activities (amylase, xylanase and carboxymethylcellulase). Compared with the unsupplemented fermenters, YHS treatment increased (P < 0.001) NH 3-N concentrations and molar proportions of propionate and butyrate at the expense of acetate, and decreased (P < 0.001) acetate:propionate ratio. In addition, YHS supplementation tended (P < 0.07) to reduce CH 4 /total VFA ratio and to increase microbial growth in the liquid phase of the fermenters. The automated ribosomal intergenic spacer analysis (ARISA) of samples taken on days 3, 8 and 14 of incubation from solid and liquid content of fermenters revealed that YHS supplementation increased (P < 0.02) bacterial Abbreviations: ADFom, acid detergent fiber expressed exclusive of residual ash; AFOM, apparently fermented OM; aNDFom, neutral detergent fiber with heat-stable amylase and expressed exclusive of residual ash; ARISA, automated ribosomal intergenic spacer analysis; CP, crude protein; BSC, 15:85 barley straw:concentrate; AHC, 50:50 alfalfa hay:concentrate; OM, organic matter; VFA, volatile fatty acids; YH, yeast hydrolyzate; YHS, yeast hydrolyzate obtained from sugarcane processing diversity in the liquid phase and tended to increase {P < 0.08) it in the solid phase. The results indicate that YHS at a dose of 10 ml/1 may be a useful dietary additive for ruminants, because it promoted a shift in fermentation toward propionate production,...

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

“…Using post-FYeB to replace SBM in ruminant diets gives an opportunity not only to use post-FYeB resourcefully, but also to lead beneficial metabolic alters in cattle. Post-FYeB or yeast cream is generated from bioethanol production and contains about 60-70% of yeast cells, thus inclusion of post-FYeB into concentrate diet may provide an additional source of protein and essential amino acids to animals (Díaz et al, 2017).…”

“…The results show that the nutrient digestibilities of DM, OM, CP, NDF, and ADF in cattle fed various levels of post-FYeB were not significantly different among diets (P > 0.05). However, the numerical improvement on CP digestibility for 100% post-FYeB was higher than that of the 100% SBM group (1.5% DM), which could be possibly due to the fact that CP of the yeast biomass is easier fermented by bacteria than that of SBM (Díaz et al, 2017). In addition, adding urea to the SBM replacement may also increase CP digestibility (Cherdthong and Wanapat, 2010).…”

“…Sacharomyces cerevisiae is also used as a microorganism fermenter for bioethanol production of molasses, and the by-product after fermentation processing is called 'yeast cream waste' which contains 60-70% yeast cells (Laluce et al, 2016;Díaz et al, 2017). This produced abundantly post-fermentative yeast biomass (post-FYeB) causes much environmental pollution, but contains many nutrients (25-30% of CP) and could be used as animal feed (Díaz et al, 2017). Therefore, utilization of post-FYeB as an alternative protein source could be beneficial in reducing feed cost and environmental pollution.…”

Screening of live yeast and yeast derivatives for their impact of strain and dose on in vitro ruminal fermentation and microbial profiles with varying media pH levels in high‐forage beef cattle diet

“…Indeed, oxygen may not be an issue because the substrate was ground through 1‐mm screen, and the bottle was purged with CO 2 to remove air from the headspace prior to being sealed. In addition, the greater NH 3 ‐N concentration with the addition of yeast products would not support increased microbial protein synthesis, although rumen proteolytic activity may be increased by yeast supplementation . Thus, an improvement in microbial digestion by the feed may be explained by an increased production of enzymes by probiotics or an alteration in rumen microbial ecology …”

“…In addition, the greater NH 3 -N concentration with the addition of yeast products would not support increased microbial protein synthesis, although rumen proteolytic activity may be increased by yeast supplementation. 30 Thus, an improvement in microbial digestion by the feed may be explained by an increased production of enzymes by probiotics or an alteration in rumen microbial ecology. 28 Yeast derivatives were also effective in the stimulation of rumen fermentation, and are considered to have a prebiotic effect.…”