Characteristics Of Blood Metabolites,Rumen Fermentation Function,Microflora And Changes In Their Metabolites At Different Physiological Stages In Small-Tailed Han Sheep

Ruminal microorganisms and their metabolites are closely related to the growth and development,nutrient metabolism and reproductive performance of livestock.In this study,adult Small-tailed Han sheep were used as the study subjects.Blood metabolites,immunological indicators,rumen fermentation,microflora and their metabolites were measured under the same diet conditions at three physiological stages:non-pregnancy,gestation period and lactation period.The aim was to investigate the characteristics of blood metabolites,immune indicators,rumen fermentation function,microbial flora and changes in their metabolites at different physiological stages in Small-tailed Han sheep ewes.The results of this study are as follows:1.The detection of blood metabolites at different physiological stages revealed that 386,519 and 453 differential metabolites were identified in the positive ion mode and 148,40 and 128 differential metabolites in the negative ion mode when comparing Np-Gp,Np-Lp and Gp-Lp,respectively.The differential metabolites were mainly enriched in tryptophan metabolism,cholesterol metabolism and amino acid synthesis-related pathways during gestation period and lactation period,thus playing an important role in cellular metabolism and immune regulation.2.Blood immune indicators differed between physiological stages,with Ig A and Ig M being significantly higher in lactation period than in gestation period and non-pregnancy（P<0.05）;Ig G was significantly higher in lactation than in pregnancy（P<0.05）.3.The Results of rumen fermentation function at different physiological stages showed differences in rumen volatile fatty acid content,with total volatile fatty acids and acetic acid significantly higher in lactation period than gestation period and non-pregnancy（P<0.05）;NH₃-N content was the highest in gestational period,which was significantly higher than in non-pregnancy and lactation period（P<0.05）.4.The results of 16S r RNA sequencing at different physiological stage showed that,at the level of phylum,Chloroflexi and Fibrobacteres were significantly higher in lactation period than in gestation period（P<0.01）;At the level of genus,the relative abundance of Prevotella＿1 was significantly higher in gestation period than in lactation period（P<0.01）,[Eubacterium]＿ruminantium＿group,Moryella and Fibrobacter had significantly lower relative abundance in non-pregnancy than in lactation period（P<0.05）,while Helicobacter and Erysipelotrichaceae＿UCG-009were significantly higher in non-pregnancy than in lactation period（P<0.05）.Microbial functional enrichment analysis showed that differential microorganisms were mainly enriched in pathways such as carbohydrate metabolism and sugar biosynthesis.5.Ruminal microbial metabolite assays at different physiological stages revealed that comparing Np-Gp,Np-Lp and Gp-Lp separately,421,489 and 342 differential metabolites were identified in the positive ion mode;104,50 and 23 differential metabolites were identified in the negative ion mode,respectively.Pathways associated with energy metabolism were significantly enriched during gestation and lactation.6.Correlation of rumen microbes and their metabolites with blood metabolites at different physiological stages.Ruminococcaceae＿UCG-010 was positively correlated with lignoceric acid（P<0.05）and[Eubacterium]＿ruminantium＿group was positively correlated with indole and beta-Cryptoxanthin（P<0.05）by correlation analysis of rumen microbes and blood metabolites were positively correlated（P<0.05）.Ruminococcaceae＿UCG-010 was positively correlated with 25-hydroxycholesterol,D-phenylalanine and L-histidine（P<0.05）and Lachnospira was positively correlated with indoleacetaldehyde（P<0.05）by correlation between rumen microorganisms and their metabolites.Erysipelotrichaceae＿UCG-009 showed a significant positive correlation with oleic acid and biotin（P<0.05）.In summary,Blood metabolites at different physiological stages are mainly involved in cellular metabolism,immune regulation,the level of body immunity is significantly higher during gestation and lactation,rumen fermentation parameters are shown to increase with the body’s energy needs,microorganisms and their metabolites are closely related to energy metabolism.provide a basis for research on gastrointestinal tract health,growth and development of Small-tailed Han sheep,improve the production efficiency of Small-tailed Han sheep breeding and provide a reference basis for germplasm conservation and utilization.