热应激对山羊粪便菌群结构及代谢产物的影响

Effects of Heat Stress on the Structure and Metabolites of Fecal Flora of Goats

[目的]研究热应激对山羊粪便菌群结构及代谢产物的影响。[方法]选择6只12月龄、体重(28.4±3.2)kg的大足黑山羊成年阉公羊,采用单因子自身对照试验设计,先后接受重度热应激(H组,温湿度指数(THI)=91)、中度热应激(M组,THI=84)和无热应激(L组,THI=71)3个阶段的处理,各阶段处理15 d,过渡期7 d。于各阶段的最后1 d 14:00采集直肠粪便用于微生物16S rRNA测序分析和代谢组学分析。[结果]3个处理组山羊粪便菌群多样性无显著差异(P>0.05)。与L组相比,H和M组山羊粪便拟杆菌门相对丰度显著降低(P<0.05),变形菌门相对丰度显著升高(P<0.05);克里斯滕森菌科R-7属、狭窄梭状芽孢杆菌1属、梭菌家族XⅢAD3011属等相对丰度显著升高(P<0.05),拟杆菌属、未编码_f_毛螺菌属等相对丰度显著降低(P<0.05);粪便中的莠去津、胆酸、牛磺胆酸盐、油酸、贯叶金丝桃素、牛磺胆酸等物质的含量显著增加(P<0.05),脯氨酸-丙氨酸、精氨酸-苏氨酸、高藜芦酸等物质的含量显著降低(P<0.05);热应激条件下粪便中的差异代谢物显著富集在牛磺酸和亚牛磺酸代谢、ABC转运蛋白、谷胱甘肽代谢及紧密连接等通路(P<0.05)。[结论]热应激导致山羊粪便菌群结构改变,不利于山羊肠道健康;还使精氨酸和初级胆汁酸的生物合成代谢通路上调,有助于山羊适应高湿热环境;导致山羊代谢物中有毒物质含量提高,可能对肠道屏障和神经系统造成损伤。

[Objective]The aim of this trial was to investigate the effects of heat stress on fecal flora structure and metabolites in goats.[Method]Six adult castrated rams of Dazu Montenegrin sheep with similar age and body weight of 28.4 kg±3.2 kg were selected,and a single factor self-control experimental design was used.They were subjected to three stages of treatment:Severe heat stress(H group,temperature and humidity index(THI)=91),moderate heat stress(M group,THI=84),and no heat stress(L group,THI=71).Each treatment stage was 15 days,and the transition period was 7 days.Rectal feces were collected at 14:00 on the last day of each stage for microbial 16S rRNA sequencing and metabolomics analysis.[Result]There was no significant difference in the diversity of goat fecal flora among the three groups(P>0.05).Compared with group L,in H and M groups,the relative abundance of Bacteroidetes was significantly decreased(P<0.05),and the relative abundance of Proteobacteria was significantly increased(P<0.05).The relative abundances of Christensenaceae R-7 group,Clostridium sensu stricto 1,and Family XⅢAD3011 group were significantly increased(P<0.05),whereas the relative abundances of Bacteroides and unclassified_f_Lachnospiraceae were significantly decreased(P<0.05).The contents of atrazine,cholic acid,taurocholate,oleic acid,hyperforin,and taurocholic acid in feces were significantly increased(P<0.05),whereas the contents of Pro-Ala,Arg-Thr and homoveratric acid were significantly decreased(P<0.05).Differential metabolites in feces under heat stress conditions were significantly enriched in the pathways of taurine and hypotaurine metabolism,ABC transporters,glutathione metabolism and gap junction(P<0.05).[Conclusion]Heat stress led to changes in the structure of goat fecal flora,which was not conducive to goat intestinal health.It also upregulated the biosynthetic metabolic pathways of arginine and primary bile acids,which helped goats adapt to high humidity and heat environments.It also led to an increase in the content of toxic substances in goat metabolites,which might cause damage to the intestinal barrier and nervous system.