饲粮中添加茶渣对奶牛体外瘤胃发酵参数和微生物多样性的影响

Effect of adding tea residue to diet on rumen fermentation parameters and microbial diversity in dairy cows

为了研究茶渣对奶牛瘤胃发酵参数和微生物菌群多样性的影响,试验基于体外模拟瘤胃发酵试验技术,采用单因子试验设计,构建了6组不同茶渣添加剂量的发酵体系,其中对照组不添加茶渣,试验Ⅰ~Ⅴ组茶渣添加量分别为饲粮干物质的5%、10%、15%、20%、25%,每个处理组3个重复,发酵24 h后,取发酵体系瘤胃液,采用16S rDNA技术进行瘤胃微生物多样性分析。结果表明:(1)饲粮中添加不同比例的茶渣对奶牛体外瘤胃发酵体系中pH和MCP浓度无显著性影响(P>0.05);随着茶渣添加量的提高,试验Ⅱ、Ⅲ、Ⅳ、Ⅴ组的NH3-N浓度均显著低于对照组、Ⅰ组(P<0.05);试验Ⅳ组乙酸、丙酸、丁酸、异丁酸浓度和TVFA含量显著高于对照组和其他各试验组(P<0.05),Ⅴ组的乙酸/丙酸值显著高于Ⅰ、Ⅱ、Ⅲ、Ⅳ组(P<0.05),Ⅰ、Ⅱ组的乙酸/丙酸值显著低于对照组、Ⅲ、Ⅳ组(P<0.05),但两者之间差异不显著。(2)组间瘤胃微生物菌群组成具有相似性,6组样本在门水平上的主要菌门均为拟杆菌门(Bacteroidota)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、螺旋体门(Spirochaetota)、疣微菌门(Verrucomicrobiota)、Patescibacteria、蓝藻菌门(Cyanobacteria)、纤维杆菌门(Fibrobacterota),茶渣添加量为饲粮干物质的25%时,与对照组相比,试验Ⅴ组拟杆菌门、螺旋体门及纤维杆菌门相对丰度显著升高(P<0.05),厚壁菌门相对丰度显著降低(P<0.05),试验Ⅰ、Ⅱ、Ⅲ及Ⅳ组差异均不显著(P>0.05)。(3)与对照组相比,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ及Ⅴ组的Ace指数、Chao1指数、Shannon指数和Simpson指数差异均不显著(P>0.05)。(4)与试验组相比,脱硫弧菌属(Desulfovibrio)、瘤胃球菌属(Ruminococcus)和克里斯滕森菌科(Christensenellaceae)在对照组富集。综上所述,本试验条件下,饲粮中添加茶渣会降低瘤胃NH3-N浓度,提高TVFA含量,提高拟杆菌门、螺旋体门及纤维杆菌门的相对丰度,降低厚壁菌门的相对丰度,但不会显著改变瘤胃微生物菌群多样性指数。

To study the effects of tea residue on rumen microflora diversity of dairy cows,six groups of fermentation systems with different tea residue supplemental dosages were constructed by single factor design based on in vitro simulated rumen fermentation test technology,in which the control group did not add tea residue,the addition levels of tea leaves in experimental groupsⅠtoⅤwere 5%,10%,15%,20%and 25%of the dietary dry matter,respectively.Each treatment group had three replicates.After 24 h fermentation,rumen fluid of fermentation system was taken and the microbial diversity in rumen was analyzed by using 16S rDN A technique.The results showed that:(1)Adding different proportions of tea residue to the diet did not significantly affect the pH and MCP concentration in the in vitro rumen fermentation system of dairy cows(P>0.05);as the amount of lea residue added increased,the NH_3-N concentrations in experimental groupsⅡ,Ⅲ,Ⅳ,andⅤwere significantly lower than those in control andⅠgroups(P<0.05);the concentration of acetic acid,propionic acid,butyric acid,isobutyric acid and TVFA content in groupⅣwere significantly higher than those in the control group and other test groups(P<0.05);the acetic acid/propionic acid value in groupⅤwas significantly higher than that in groupⅠ,Ⅱ,Ⅲ,andⅣ(P<0.05);the acetic acid/propionic acid value in groupⅠandⅡwas significantly lower than that in the control group,Ⅲ,andⅣ(P<0.05),but there was no significant difference between the two groups.(2)The composition of rumen microflora was similar between groups.At the phylum level,the main phyla of all the six groups were Bacteroidota,Firmicutes,Proteobacteria,Spirochaetota,Verrucomicrobiota,Patescibacteria,Cyanobacteria and Fibrobacterota.When the tea residue supplemental level was 25%of dietary dry matter,the relative abundance of Bacteroidota,Spirochaetota and Fibrobacterota in test V group was significantly increased compared with the control group(P<0.05),the relative abundance of Firmicutes was significantly decreased(P<0.05),there was no significant difference betweenⅠ,Ⅱ,ⅢandⅣgroup(P>0.05).(3)Compared with the control group,there were no significant differences in Ace index,Chao1 index,Shannon index and Simpson index inⅠ,Ⅱ,Ⅲ,ⅣandⅤgroups(P>0.05).(4)Compared with the experimental group,Desulfovibrio,Ruminococcus and Christensenellaceae were enriched in the control group.In conclusion,the addition of tea residue in the diet would reduce the concentration of NH_3-N and increase the content of TVFA in the rumen,and the relative abundance of Bacteroidetes,Spirochaetota and Fibrobacterota were increased and the relative abundance of Firmicutes was decreased,but the rumen microflora diversity index of dairy cows was not significantly affected by tea residue.