Effects of Saccharomyces cerevisiae fermentation products on performance and rumen fermentation and microbiota in dairy cows fed a diet containing low quality forage

Background： A possible option to meet the increased demand of forage for dairy industry is to use the agricultural byproducts, such as corn stover. However, nutritional value of crop residues is low and we have been seeking technologies to improve the value. A feeding trial was performed to evaluate the effects of four levels of Saccharomyces cerevisiae fermentation product（SCFP; Original XP; Diamond V） on lactation performance and rumen fermentation in mid-lactation Holstein dairy cows fed a diet containing low-quality forage. Eighty dairy cows were randomly assigned into one of four treatments： basal diet supplemented with 0, 60, 120, or 180 g/d of SCFP per head mixed with 180, 120, 60, or 0 g of corn meal, respectively. The experiment lasted for 10 wks, with the first 2 weeks for adaptation.Results： Dry matter intake was found to be similar（P 〉 0.05） among the treatments. There was an increasing trend in milk production（linear, P ≤ 0.10） with the increasing level of SCFP supplementation, with no effects on contents of milk components（P 〉 0.05）. Supplementation of SCFP linearly increased（P 〈 0.05） the N conversion, without affecting rumen pH and ammonia-N（P 〉 0.05）. Increasing level of SCFP linearly increased（P 〈 0.05） concentrations of ruminal total volatile fatty acids, acetate, propionate, and butyrate, with no difference in molar proportion of individual acids（P 〉 0.05）. The population of fungi and certain cel ulolytic bacteria（Ruminococcus albus, R. flavefaciens and Fibrobacter succinogenes）increased linearly（P 〈 0.05） but those of lactate-utilizing（Selenomonas ruminantium and Megasphaera elsdeni） and lactate-producing bacteria（Streptococcus bovis） decreased linearly（P ≤ 0.01） with increasing level of SCFP. The urinary purine derivatives increased linearly（P 〈 0.05） in response to SCFP supplementation, indicating that SCFP supplementation may benefit for microbial protein synthesis in the rumen.Conclusions： The SCFP supplementation was effective in maintaining milk persistency of mid-lactation cows receiving diets containing low-quality forage. The beneficial effect of SCFP could be attributed to improved rumen function; 1）microbial population shift toward greater rumen fermentation efficiency indicated by higher rumen fungi and cel ulolytic bacteria and lower lactate producing bacteria, and 2） rumen microbial fermentation toward greater supply of energy and protein indicated by greater ruminal VFA concentration and increased N conversion. Effects of SCFP were dose-depended and greater effects being observed with higher levels of supplementation and the effect was more noticeable during the high THI environment.

外源添加产乙酸菌和酿酒酵母发酵物对瘤胃发酵特性及产乙酸菌菌群结构的影响（英文）

目的:酵母可以促进产乙酸菌利用氢生成乙酸。为了解产乙酸菌在瘤胃发酵中的作用,本试验研究了产乙酸菌单独添加及其与酿酒酵母发酵物联合添加对瘤胃发酵特性及产乙酸菌菌群结构的影响。创新点:通过瘤胃甲烷生成量与产乙酸菌菌群结构关联,揭示降低瘤胃甲烷生成的新途径。方法:试验采用2×2双因素试验设计,产乙酸菌TWA4的添加量为0和2×107 cells/ml,酿酒酵母发酵物XP的添加量为0和2 g/L。结论:瘤胃体外发酵研究发现,单独添加XP以及TWA4和XP联合添加可增加挥发性脂肪酸产量(P<0.05),TWA4和XP联合添加显著增加了甲烷生成量(P<0.05)。单独添加TWA4、XP以及两者联合添加均增加了含有甲酰四氢叶酸合成酶的微生物的数量,尤其是产乙酸菌的数量,这类微生物的增长幅度高于产甲烷菌。各处理产乙酸菌均以Lachnospiraceae为主,但与已培养的微生物的相似性较低。与Acetitomaculum ruminis低相似性的一类未知的产乙酸菌在各处理中均占优势,但XP的添加增加了与Eubacterium limosum低相似未知产乙酸菌的数量。与XP不同,TWA4及其与XP的联合添加使与A.ruminis低相似性的一类未知的产乙酸菌的数量增加,与E.limosum低相似未知产乙酸菌的数量降低。因此,添加与E.limosum低相似的未知产乙酸菌和(或)酵母可能是降低瘤胃甲烷生成的一种有效途径。