Potential roles of the rectum keystone microbiota in modulating the microbial community and growth performance in goat model

Background Ruminal microbiota in early life plays critical roles in the life-time health and productivity of ruminant animals.However,understanding of the relationship between gut microbiota and ruminant phenotypes is very limited.Here,the relationship between the rectum microbiota,their primary metabolites,and growth rate of a total of 76 young dairy goats(6-month-old)were analyzed,and then 10 goats with the highest or lowest growth rates respectively were further compared for the differences in the rectum microbiota,metabolites,and animal’s immune parameters,to investigate the potential mechanisms by which the rectum microbiota contributes to the health and growth rate.Results The analysis of Spearman correlation and microbial co-occurrence network indicated that some keystone rectum microbiota,including unclassified Prevotellaceae,Faecalibacterium and Succinivibrio,were the key modulators to shape the rectum microbiota and closely correlated with the rectum SCFA production and serum IgG,which contribute to the health and growth rate of young goats.In addition,random forest machine learning analysis suggested that six bacterial taxa in feces could be used as potential biomarkers for differentiating high or low growth rate goats,with 98.3%accuracy of prediction.Moreover,the rectum microbiota played more important roles in gut fermentation in early life(6-month-old)than in adulthood stage(19-month-old)of goats.Conclusion We concluded that the rectum microbiota was associated with the health and growth rate of young goats,and can be a focus on the design of the early-life gut microbial intervention.

Yak rumen microbiome elevates fiber degradation ability and alters rumen fermentation pattern to increase feed efficiency

Rumen microbes play an important role in ruminant energy supply and animal performance.Previous studies showed that yak(Bos grunniens)rumen microbiome and fermentation differ from other ruminants.However,little is understood about the features of the rumen microbiome that make yak adapted to their unique environmental and dietary conditions.This study was to investigate the rumen microbiome and metabolome to understand how yak adapt to the coarse forage and harsh environment in the Qinghai-Tibetan plateau.Nine female Qaidam yellow cattle(Bos taurus),9 dzomo(hybrids of cattle and yak)and 9 female plateau yak(B.grunniens),about 5 to 6 years old,were used in this study.Rumen fermentation parameters,fibrolytic enzyme activities,and rumen metataxonomic were determined.Then 18(6 samples per group)were selected for rumen metagenomic and metabolome analysis.Metataxonomic analysis revealed that the rumen microbiota was significantly different among plateau yak,Qaidam yellow cattle,and dzomo(P<0.05).Metagenomic analysis displayed a larger gene pool encoding a richer repertoire of carbohydrate-active enzymes in the rumen microbiome of plateau yak and dzomo than Qaidam yellow cattle(P<0.05).Some of the genes encoding glycoside hydrolases that mediate the digestion of cellulose and hemicellulose were significantly enriched in the rumen of plateau yak than Qaidam yellow cattle,but glycoside hydrolase 57 that primarily includes amylases was abundant in Qaidam yellow cattle(P<0.05).The rumen fermentation profile differed also,Qaidam yellow cattle having a higher molar proportion of acetate but a lower molar proportion of propionate than dzomo and plateau yak(P<0.05).Based on metabolomic analysis,rumen microbial metabolic pathways and metabolites were different.Differential metabolites are mainly amino acids,carboxylic acids,sugars,and bile acids.Changes in rumen microbial composition could explain the above results.The present study showed that the rumen microbiome of plateau yak helps its host to adapt to the Qinghai-Tibetan plateau.In particular,the plateau yak rumen microbiome has more enzymes genes involved in cellulase and hemicellulase than that of cattle,resulting higher fibrolytic enzyme activities inyak,further providing stronger fiber degradation function.

Low rumen degradable starch promotes the growth performance of goats by increasing protein synthesis in skeletal muscle via the AMPK-mTOR pathway

Since starch digestion in the small intestine provides more energy than digestion in the rumen of ru-minants,reducing dietary rumen degradable starch(RDS)content is beneficial for improving energy utilization of starch in ruminants.The present study tested whether the reduction of rumen degradable starch by restricting dietary corn processing for growing goats could improve growth performance,and further investigated the possible underlying mechanism.In this study,twenty-four 12-wk-old goats were selected and randomly allocated to receive either a high RDS diet(HRDS,crushed corn-based concen-trate,the mean of particle sizes of corn grain=1.64 mm,n=12)or a low RDS diet(LRDS,non-processed corn-based concentrate,the mean of particle sizes of corn grain>8 mm,n=12).Growth performance,carcass traits,plasma biochemical indices,gene expression of glucose and amino acid transporters,and protein expression of the AMPK-mTOR pathway were measured.Compared to the HRDS,LRDS tended to increase the average daily gain(ADG,P=0.054)and decreased the feed-to-gain ratio(F/G,P<0.05).Furthermore,LRDS increased the net lean tissue rate(P<0.01),protein content(P<0.05)and total free amino acids(P<0.05)in the biceps femoris(BF)muscle of goats.LRDS increased the glucose concen-tration(P<0.01),but reduced total amino acid concentration(P<0.05)and tended to reduce blood urea nitrogen(BUN)concentration(P=0.062)in plasma of goats.The mRNA expression of insulin receptors(INSR),glucose transporter 4(GLUT4),L-type amino acid transporter 1(LAT1)and 4F2 heavy chain(4F2hc)in BF muscle,and sodium-glucose cotransporters 1(SGLT1)and glucose transporter 2(GLUT2)in the small intestine were significantly increased(P<0.05)in LRDS goats.LRDS also led to marked activation of p70-S6 kinase(S6K)(P<0.05),but lower activation of AMP-activated protein kinase(AMPK)(P<0.05)and eukaryotic initiation factor 2a(P<0.01).Our findings suggested that reducing the content of dietary RDS enhanced postruminal starch digestion and increased plasma glucose,thereby improving amino acid utilization and promoting protein synthesis in the skeletal muscle of goats via the AMPK-mTOR pathway.These changes may contribute to improvement in growth performance and carcass traits in LRDS goats.

Rumen bacterial cluster identification and its influence on rumen metabolites and growth performance of young goats

Enterotypes,which are defined as bacterial clusters in the gut microbiome,have been found to have a close relationship to host metabolism and health.However,this concept has never been used in the rumen,and little is known about the complex biological relationships between ruminants and their rumen bacterial clusters.In this study,we used young goats(n=99)as a model,fed them the same diet,and analyzed their rumen microbiome and corresponding bacterial clusters.The relationships between the bacterial clusters and rumen fermentation and growth performance in the goats were further investigated.Two bacterial clusters were identified in all goats:the P-cluster(dominated by genus Prevotella,n=38)and R-cluster(dominated by Ruminococcus,n=61).Compared with P-cluster goats,Rcluster goats had greater growth rates,concentrations of propionate,butyrate,and 18 free amino acids)and proportion of unsaturated fatty acids,but lower acetate molar percentage,acetate to propionate ratio,and several odd and branched chain and saturated fatty acids in rumen fluid(P<0.05).Several members of Firmicutes,including Ruminococcus,Oscillospiraceae NK4A214 group,and Christensenellaceae R-7 group were significantly higher in the R-cluster,whereas Prevotellaceae members,such as Prevotella and Prevotellaceae UCG-003,were significantly higher in P-cluster(P<0.01).Co-occurrence networks showed that R-cluster enriched bacteria had significant negative correlations with P-cluster enriched bacteria(P<0.05).Moreover,we found the concentrations of propionate,butyrate and free amino acids,and the proportions of unsaturated fatty acids were positively correlated with R-cluster enriched bacteria(P<0.05).The concentrations of acetate,acetate to propionate ratio,and the proportion of odd and branched chain and saturated fatty acids were positively correlated with P-cluster enriched bacteria(P<0.05).Overall,our results indicated that rumen bacterial clusters can influence rumen fermentation and growth performance of young goats,which may shed light on modulating the rumen microbiome in early life to improve the growth performance of ruminant animals.