Effects of dietary supplementation with 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester on ileal microbiota and metabolism in Liaoning cashmere goats

Currently, rumen-protected methionine, such as 2-hydroxy-4-(methylthio)butanoic acid isopropyl ester (HMBi), is frequently employed in the ruminant breeding industry to reduce microbial degradation and subsequently enhance the methionine supply in an effective manner. However, there is a paucity of information regarding alterations in the microecological status of the small intestine with HMBi supplementation. Hence, the present study integrated multi-omics approaches to reveal the effects of HMBi on the microbial community, metabolites, and production performance in the ileum of Liaoning Cashmere goats. In this study, 14 female goats were assigned to be fed the control diets (CON, n = 7) and HMBi (n = 7) diets. After 67 days, the ileal digesta were sampled for measurements. Our results showed that the HMBi diets significantly increased ( P  < 0.05) the cashmere length and growth rate, and tended to increase the ileal MCP concentration ( P  = 0.085). Our results of ileal microbiota demonstrated that the HMBi supplementation decreased the abundance of cellulose-degrading bacteria (Cellulosilyticum, Lachnospiraceae_uncultured, Breznakia, etc.) and increased the abundance of beneficial bacteria (OTU9, OUT256, OTU657, etc.) in the ileum of goats. Our results of ileal metabolites also showed that, the content of HMBi degradation products (such as HMB and methionine) and some substance (such as taxifolin, Soyasaponin I, and tyrosol) enhanced the intestinal health in the ileum of goats were increased after HMBi feeding ( P  < 0.05). Moreover, our Mantel tests showed that ileal microbiota and metabolites significantly contributed to the improved cashmere performance of goats ( P  < 0.05). Overall, the above results revealed that the ileal microbiota and metabolism were involved in the process of HMBi regulating cashmere performance of goats.