过瘤胃蛋氨酸对藏西北白绒山羊部分消化道酶活及瘤胃和空肠微生物菌群的影响OA

This experiment aimed to investigate the effects of rumen-protected methionine on the activ-ities of certain digestive enzymes and the microbial communities in the rumen and jejunum of Northwest Xizang cashmere goats.Sixteen healthy 12-month-old Northwest Xizang white cashmere goats(males and females equally divided)were randomly assigned into two groups with eight replicates per group and one goat per replicate.The control group(CON)was fed a basal diet,while the experimental group(RPMet)was fed the basal diet supplemented with 0.5％rumen-protected methionine.The adaptation period lasted one week,followed by a seven-week experimental period.The results showed that compared with the CON group:(1)rumen pepsin activity in the RPMet group was extremely increased(P＜0.01);jejunal and ce-cal trypsin activities were also extremely increased(P＜0.01);and colonic and cecal chymotrypsin activi-ties were extremely increased(P＜0.01).(2)The Chao1 index of the rumen microbiota in the RPMet group was increased(P＜0.05).(3)At the phylum level,the relative abundance of Firmicutes in the ru-men microbiota of the RPMet group was extremely increased(P＜0.01);at the genus level,the relative a-bundances of Prevotella,Ruminococcus,and Succiniclasticum in the rumen microbiota of the RPMet group were significantly increased(P＜0.01).(4)The degradation pathways of valine,leucine,and iso-leucine were extremely upregulated(P＜0.01),while the biosynthetic pathways of biotin and tryptophan metabolism were significantly upregulated(P＜0.05).In conclusion,dietary supplementation with rumen-protected methionine increased the activities of certain digestive proteases,altered the rumen microbial community structure,and influenced amino acid metabolism of the rumen microbiota in cashmere goats,thereby enhancing,to a certain extent,the digestive capacity of the rumen microbiota for dietary fiber.