饲粮精粗比转换下的牦牛粪便菌群区系演替

Succession of microbial community in yak feces under transition of feed concentrate to roughage ratio

试验旨在研究饲粮精粗比转换对牦牛粪便微生物分布及功能的影响。选取24头体重接近、健康的3周岁公牦牛,1~60 d饲喂精粗比为30∶70的饲粮(C30组),61~120 d转换为精粗比为70∶30的饲粮(C70组)。预试期15 d,正式试验期120 d。试验第60 d和120 d,饲喂3~4 h后随机选取6头试验牦牛,采用直肠粪便采样法收集约50 g粪便,通过16S rRNA基因测序技术进行测序,比较分析粪便微生物区系,进行PICRUSt2功能预测。结果显示,两组谱系多样性及多样性指数差异均不显著(P>0.05)。通过PCoA分析发现,两组牦牛的粪便菌群的组成存在明显差异(P<0.05)。在门水平上,C70组中放线菌门(Actinobacteriota)相对丰度显著高于C30组(P<0.05)。在属水平上,C70组中的未分类菌属(unidentified)的相对丰度极显著高于C30组(P<0.01),未培养细杆菌(uncultured_bacterium)和罗氏菌属(Roseburia)的相对丰度显著高于C30组(P<0.05),毛螺旋菌属_NK3A20_群(Lachnospiraceae_NK3A20_group)、欧陆森氏菌属(Olsenella)、索氏梭菌属(Paeniclostridium)的相对丰度显著高于C70组(P<0.05)。在KEGG水平2上,C70组能量代谢、萜类和多酮类化合物的代谢、异种生物降解和代谢等功能的表达水平低于C30组。研究表明,饲粮精粗比转换影响了牦牛粪便菌群的丰度和多样性,并影响了牦牛粪便中菌群的组成,从低精粗比饲粮转换为高精粗比饲粮降低了后肠道中纤维降解菌的相对丰度,促进了产酸菌的增殖,增加了索氏梭菌属的比例。

The study aimed to investigate the impact of the feed concentrate to roughage ratio transition on the microbial distribution and functions in yak feces.Twenty-four healthy male yaks at three years old with similar weight were fed a diet of 30∶70 for 1~60 days(Group C30),and converted to a diet of 70∶30 for 61~120 days(Group C70).The pre-test period was 15 days,and the formal test period was 120 days.Fecal samples were collected using the rectal fecal sampling method from six randomly selected yaks on day 60 and day 120 after feeding for 3~4 hours.The samples were sequenced using 16S rRNA gene sequencing technology to compare and analyze the fecal microbial community,and functional predictions were made using PICRUSt2.The results showed no significant differences in lineage diversity and diversity indices between the two groups(P>0.05).PCoA analysis revealed a significant difference in the composition of fecal microbial communities between the two groups(P<0.05).At the phylum level,the relative abundance of Actinobacteriota in Group C70 was significantly higher than in Group C30(P<0.05).At the genus level,the relative abundance of unidentified taxa in Group C70 was extremely higher than in Group C30(P<0.01),and the relative abundance of uncultured bacterium and Roseburia was significantly higher in Group C70 than in Group C30(P<0.05),while the relative abundance of Lachnospiraceae_NK3A20_group,Olsenella,and Paeniclostridium was significantly higher in Group C30 than in Group C70(P<0.05).At the KEGG level 2,the expression levels of functions such as energy metabolism,terpenoid and polyketide metabolism,interspecies biodegradation,and metabolism were lower in Group C70 compared to Group C30.The study indicates that the transition of feed concentrate to roughage ratio affects the richness and diversity of fecal microbial communities, significantly influencing the composition of microbial communities in yak feces. Transitioning from a low concentrate to roughage ratio to a high ratio reduces the relative abundance of fiber-degrading bacteria in the hindgut,promotes the proliferation of acid-producing bacteria, increases the proportion of Paeniclostridium.