饲粮添加苜蓿黄酮对奶牛瘤胃菌群的影响

Effects of alfalfa flavonoids as dietary additives on bacterial flora in the rumen of dairy cows

本试验旨在研究苜蓿黄酮对奶牛瘤胃菌群结构和组成的影响。选取4头装有瘘管的头胎荷斯坦奶牛,试验采用4×4拉丁方设计,每头奶牛每天饲喂全混合饲粮(TMR),其中分别添加0g(A组)、20g(B组)、60g(C组)和100g(D组)苜蓿黄酮。试验分为4期,每期24d。每期采集瘤胃液,提取总DNA后在Illumina MiSeq平台上进行测序。结果为:1)4个处理组共产生52747个OTU,共享16142个OTU,占总OTU数量的30.60%,其中试验A组的OTU数量最高。2)Shannon指数随着苜蓿黄酮添加剂量的升高呈先上升后下降的趋势,试验C组的Simpson指数显著高于试验D组和A组(P<0.05),但各处理组间的ACE和Chao 1指数无显著性差异。3)各试验组间的细菌门的数量没有显著性差异,但试验C组的细菌属的数量显著高于试验B组和试验A组(P<0.05)。在门水平上,SR1门相对丰度随着苜蓿黄酮添加水平的升高呈线性升高的趋势(0.05<P<0.10);互养菌门相对丰度随着苜蓿黄酮添加剂量的增加呈先下降后升高的趋势(0.05<P<0.10)。在属水平上,试验B组RC9和SP3-e08属相对丰度显著高于试验A组,而Oribacterium属相对丰度则与之相反;Shuttleworthia属相对丰度随苜蓿黄酮添加剂量的升高呈线性升高(P<0.05),其中试验D组的相对丰度高于试验A组。4)通过聚类分析,试验A和B组细菌群落结构比较相似,试验C和D组细菌群落结构比较相似。结果表明,饲粮中添加苜蓿黄酮能够改变瘤胃细菌的群落结构和组成,进而影响营养物质的消化和代谢。

The objective of this study was to examine the effects of alfalfa flavonoids on the bacterial flora in the rumen of dairy cows.Four primiparous Holstein cows fitted with ruminal cannulas were used in a 4×4Latin square design and were fed a total mixed ration containing 0,20,60,or 100 g alfalfa flavonoids per day（group A-D,respectively）.The experiment had four periods and each period lasted 24 days.The ruminal fluid was collected during each period.Total bacterial DNA was extracted from the ruminal fluid,and 16 S RNA sequences were obtained using the Illumina MiSeq platform.In total,52747 operational taxonomic units（OTUs）were generated,and 16142 OTUs were shared by four groups,accounting for 30.60% of the total OTUs.The largest amount of OTUs was in group A.As the amount of alfalfa flavonoids in the diet increased,the Shannon index first increased and then decreased,but the abundance-based coverage estimator and Chao 1indexes were unaffected.Simpson＇s index was significantly higher for group C than for groups A and D（P0.05）.There were more bacterial genera in group C than in groups B and A,but the number of phyla in each group was not affected by the amount of alfalfa flavonoids in the diet.At the phylum level,the relative abundance of SR1 tended to increase linearly（0.05P0.10）,and the relative abundance of Synergistetes first decreased and then increased（0.05P0.10）as the amount of alfalfa flavonoids in the diet increased.At the genus level,the relative abundance of RC9 and SP3-e08 was higher in group B than in group A,while the relative abundance of Oribacterium was higher in group A than in group B.The relative abundance of Shuttleworthiaincreased linearly with increasing alfalfa flavonoids（P0.05）,and the relative abundance of Shuttleworthia was significantly higher in group D than in group A.In a clustering analysis,the bacterial community structure was similar in groups A and B,and in groups C and D.In conclusion,dietary supplementation with alfalfa flavonoids can change the composition and community structure of ruminal bacteria,thus affecting metabolism and nutrient digestion.