饲粮中添加酵母培养物对舍饲牦牛瘤胃发酵参数及微生物区系的影响

Effects of Yeast Culture Supplementation in Diets on Rumen Fermentation Parameters and Microflora of House-Feeding Yak

本试验旨在研究饲粮中添加酵母培养物(YC)对舍饲牦牛瘤胃发酵参数及微生物区系的影响。试验选取4岁、初始体重为(180.31±29.73)kg的健康麦洼公牦牛36头,随机分为4组,每组9个重复,每个重复1头牦牛,分别饲喂YC添加水平为0(Ⅰ组)、0.5%(Ⅱ组)、1.0%(Ⅲ组)和1.5%(Ⅳ组)的全混合日粮。预试期10 d,正试期80 d。结果表明:1)随着饲粮YC添加水平的升高,瘤胃微生物蛋白(MCP)含量显著升高(P<0.05),pH有呈线性降低的趋势(P=0.058),氨态氮(NH3-N)含量有呈二次曲线变化的趋势(P=0.055),乙酸比例及乙酸/丙酸呈显著线性降低(P<0.05),丙酸和丁酸比例呈显著线性增加(P<0.05),总挥发性脂肪酸(TVFA)含量无显著变化(P>0.05)。2)舍饲牦牛瘤胃微生物多样性指数除Chao指数外,其余各指数组间无显著差异(P>0.05)。3)门水平上,4组的优势菌门均为拟杆菌门、厚壁菌门和变形菌门。随着饲粮YC添加水平的升高,疣微菌门的相对丰度呈显著线性升高(P<0.05),Saccharibacteria的相对丰度呈显著线性降低(P<0.05),互养菌门的相对丰度呈显著二次曲线变化(P<0.05),变形菌门和纤维杆菌门的相对丰度有呈二次曲线变化的趋势(P=0.065,P=0.064)。属水平上,普雷沃菌属、拟杆菌目BS11和理研菌科RC9为优势菌属,随着饲粮YC添加水平的升高,克里斯滕森菌科R7的相对丰度呈显著线性降低(P<0.05),与pH和NH3-N含量呈显著正相关(r>0.500,P<0.05),奎因氏菌属的相对丰度呈显著线性降低(P<0.05),与TVFA含量呈显著正相关(r=0.460,P<0.05),瘤胃球菌科UCG-001和瘤胃球菌科UCG-014的相对丰度呈显著线性降低(P<0.05),与pH呈显著正相关(r>0.500,P<0.05),瘤胃球菌科UCG-011和瘤胃球菌属2的相对丰度呈显著二次曲线变化(P<0.05)。综上所述,在舍饲牦牛饲粮中添加YC显著影响了瘤胃中微生物的丰富度,影响门和属水平微生物的组成,进而对瘤胃发酵参数产生影响。

This experiment was to investigate the effects of yeast culture supplementation in diets on the rumen fermentation parameters and microflora of house-feeding yak.Thirty-six healthy Maiwa male yaks with 4 years of age and an initial body weight of(180.31±29.73)kg were randomly divided into 4 groups with 9 replicates in each group and 1 yak in each replicate,and were fed total mixed rations with yeast culture supplementation levels of 0(Ⅰ),0.5%(Ⅱ),1.0%(Ⅲ)and 1.5%(Ⅳ),respectively.The experiment lasted for 90 d,with 10 d of adaptation period and 80 d of trial period.The results showed as follows:1)with the increase of dietary yeast culture levels,rumen microbial proteins(MCP)content significantly increased(P<0.05),pH had a tendency decreased linearly(P=0.058),ammoniacal nitrogen(NH3-N)content had a tendency of quadratic variation(P=0.055),the percentage of acetate and the value of acetate to propionate decreased linearly(P<0.05),the percentages of propionate and butyrate increased linearly(P<0.05),and total volatile fatty acids(TVFA)content had no significant change(P>0.05).2)Except for the Chao index,there was no significant difference in the rumen microbial diversity indexes of house-feeding yak(P>0.05).3)At the phylum level,Bacteroidetes,Firmicutes and Proteobacteria were the dominant phylum,with the increase of dietary yeast culture levels,the relative abundance of Verrucomicrobia increased linearly(P<0.05),the relative abundance of Saccharibacteria decreased linearly(P<0.05),and the relative abundance of Synergistetes showed quadratic variation(P<0.05),the relative abundance of Proteobacteria and Fibrobacteres showed a tendency of quadratic variation(P=0.065,P=0.064).At the genus level,prominent genus of all groups were Prevotella 1,Bacteroidales_BS11_gut_group and Rikenellaceae RC9_gut_group,with the increase of dietary yeast culture levels,the relative abundance of Christensenellaceae_R-7_group decreased linearly(P<0.05),and was positively correlated with pH and NH3-N content(r>0.500,P<0.05),the relative abundance of Quinella decreased linearly(P<0.05),and was positively correlated with TVFA content(r=0.460,P<0.05),the relative abundance of Ruminococcaceae_UCG-001 and Ruminococcaceae_UCG-014 decreased linearly(P<0.05),and was positively correlated with pH(r>0.500,P<0.05),the relative abundance of Ruminococcaceae_UCG-011 and Ruminococcus_2 showed quadratic variation(P<0.05).In conclusion,under the conditions of this experiment,the dietary yeast culture levels significantly affect microbial richness in the rumen and the level of phylum and genus of microorganisms,finally affect the rumen fermentation parameters.