Effects of Rumen-Protected Taurine Supplementation on Ruminal Fermentation, Hematological Profiles, Liver Function, and Immune Responses in Yaks

The present study evaluated the effects of dietary rumen-protected taurine (RPT) supplementation on ruminal fermentation, hematological parameters, liver function, stress-related hormones, and immune responses in yaks. Eighteen yaks were randomly allocated to three groups: a control group receiving no RPT (CON), a low-dose group receiving 20 g/day (RPT20), and a high-dose group receiving 40 g/day (RPT40). Supplementation with RPT did not significantly affect ruminal pH, microbial protein concentration, ammonia nitrogen, total volatile fatty acids, or the individual volatile fatty acid profiles (<i>p</i> > 0.05). A decreasing trend in red blood cell count was observed (<i>p</i> = 0.050), while no significant changes were detected in white blood cell or platelet indices (<i>p</i> > 0.05). Liver function markers, including albumin, alanine transaminase, aspartate transaminase, and total protein, remained unchanged, although a trend toward altered alkaline phosphatase activity was noted (<i>p</i> = 0.074). No significant effects were observed on acute-phase proteins (serum amyloid A, C-reactive protein) or stress-related hormones (epinephrine, adrenocorticotropic hormone, cortisol) (<i>p</i> > 0.05). Importantly, serum immunoglobulin A and immunoglobulin G levels were significantly increased in response to RPT supplementation (<i>p</i> = 0.029 and <i>p</i> = 0.043, respectively), suggesting enhanced humoral immunity. These findings indicate that RPT may improve immune function in yaks without negatively affecting rumen fermentation or liver health.