Effects of Rumen-Protected Glucose in Diets and Rumen-Protected Taurine Supplementation on the Colonic Mucosal Barrier in Yaks.

The intestinal barrier plays a critical role in maintaining gastrointestinal health and nutrient utilization in yaks. This study investigated the effects of dietary RPG level and RPT supplementation on colonic barrier function and microbial composition in yaks. Twenty-eight healthy male yaks (3 years old; 192.7 ± 4.52 kg) were assigned to a 2 × 2 factorial design with two dietary rumen-protected glucose (RPG) levels (1.0% or 3.0% of dietary DM) and two rumen-protected taurine (RPT) supplementation levels (5 or 20 g/animal/day) for 63 days. High-level RPG impaired colonic physical barrier function by reducing tight junction protein expression and microbial diversity, whereas high-level RPT mainly compromised chemical and immune barrier function by decreasing diamine oxidase activity, mucin-2, and secretory immunoglobulin A, accompanied by alterations in the colonic microbial community. Significant interactions between RPG and RPT were observed for several barrier- and microbiota-related indices. Overall, the effects of RPG and RPT on colonic health were dose-dependent, and moderate supplementation, particularly the combination of 1.0% dietary RPG and 5 g/day RPT, was the most effective in maintaining colonic barrier integrity and microbial homeostasis in yaks.