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

## TL;DR

This study shows that rumen-protected taurine boosts immune proteins in yaks without harming their liver or rumen health.

## Contribution

The study introduces rumen-protected taurine as a novel supplement to enhance yak immunity under intensive feeding conditions.

## Key findings

- RPT supplementation increased serum IgA and IgG levels, indicating improved humoral immunity.
- RPT had no significant negative effects on ruminal fermentation or liver function markers.
- A decreasing trend in red blood cell count was observed, possibly linked to high-altitude adaptation.

## Abstract

Yaks are essential to the livelihoods of herders on the Qinghai–Tibet plateau, but the transition to off-site intensive fattening systems has raised concerns about their nutritional and immune health. Due to environmental factors, such as altitude, temperature fluctuations, and dietary changes, yaks are susceptible to stress and compromised immune function. Taurine, a nutrient known for its immune-boosting and stress-resilience properties, is rapidly degraded in the rumen, limiting its availability. This study investigated the effects of rumen-protected taurine (RPT) supplementation on yaks. The results showed that RPT supplementation did not significantly alter ruminal fermentation or liver function. However, it significantly increased the serum levels of immune proteins IgA and IgG. Additionally, RPT supplementation was associated with changes in red blood cell counts, which may reflect an adaptive response to the high-altitude environment. These findings suggest that RPT supplementation can enhance immune function in stall-fed yaks without negatively impacting liver health.

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 (p > 0.05). A decreasing trend in red blood cell count was observed (p = 0.050), while no significant changes were detected in white blood cell or platelet indices (p > 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 (p = 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) (p > 0.05). Importantly, serum immunoglobulin A and immunoglobulin G levels were significantly increased in response to RPT supplementation (p = 0.029 and p = 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.