Rumen-protected betaine supplementation improves ileal function by affecting microbe and metabolite in Tibetan sheep

The research explored the effect of dietary rumen-protected betaine (RPB) supplementation on development and function of ileum in Tibetan sheep. Sixty male lambs (17.72 ± 0.19 kg, aged 2 months) were randomly divided into control group (Ctrl) and RPB group (0.08% Bet). The adaptation feeding period was 10 days, and the experimental period was 90 days. Results suggested that dietary RPB significantly increased villus height, villus height-to-crypt depth (VH/CD) ratio, total antioxidant capacity (T-AOC) (P < 0.05), and decreased malondialdehyde (MDA), lipopolysaccharide (LPS), tumor necrosis factor-α (TNF-α) (P < 0.05), as well as altered the composition of short-chain fatty acids (SCFAs). Importantly, expression of ileal barrier-related gene (Claudin-1) was elevated (P < 0.05). Microbial analyses showed RPB supplementation increased the relative abundances of Aeriscardovia and Bifidobacterium. Several differential metabolites, including Cer 18:1;2O/18:0, Cer 18:1;2O/24:2 and (±)13-HpODE, were significantly increased in the RPB group (P < 0.05). The VH/CD was positively correlated with Bifidobacterium, Cer 18:1;2O/18:0, Cer 18:1;2O/24:2 and (±)13-HpODE (r > 0.5). To sum up, our results suggest that the dietary RPB supplementation could affect the ileal SCFA concentration by modulating the microbial community and regulating metabolism, thereby contributing to ileal development and barrier function. This study offers new evidence supporting the use of RPB as a potential application for Tibetan sheep.