The yak ( Bos grunniens ) is of great importance to the local ecosystem and animal husbandry on the Tibetan Plateau. However, the impacts of different feeding practices on yak growth, health, and ecosystem interactions are not fully understood. This study investigates the effects of warm-season grazing and housing-feeding on yak growth performance, antioxidant capacity, immune function, metabolome, and fecal microbiota. The study found that grazing significantly increased the final body weight and average daily gain of yak ( P < 0.05), reduced serum globulin and urea nitrogen levels, and elevated aspartate aminotransferase (AST) levels. Grazing enhanced serum total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC). It also increased levels of immunoglobulins (IgA, IgM, IgG) and pro-inflammatory cytokines (IL-2, IL-6, TNF-α, IFN-γ). Meanwhile, grazing decreased levels of IL-4 and IL-10. Additionally, grazing significantly altered the plasma metabolite profile, particularly in bile acid metabolism pathways. The relative abundance of beneficial microbial genera (e.g., Christensenellaceae_R-7_group , Monoglobus , Romboutsia ) in the feces of grazing yak was significantly higher, while total short-chain fatty acids were lower than in penned yak. Grazing improved growth performance and nutritional metabolism efficiency, enhanced antioxidant and immune functions, and optimized the structure of the gut microbiota in yak. These findings indicate that grazing can better utilize natural forage resources to promote yak health and improve production performance. IMPORTANCE: This study investigates how different feeding patterns—grazing versus housing-feeding—affect the health, growth, and microbiome of yaks in the warm season. Yaks are vital to the Tibetan Plateau’s ecosystem and local livelihoods. Understanding how feeding practices impact their health can help optimize yak management, ensuring better welfare and productivity. Grazing yaks showed improved growth, enhanced antioxidant and immune functions, and a healthier gut microbiota compared to penned yaks. These findings highlight the importance of natural forage in promoting yak health and could guide sustainable yak husbandry practices, benefiting both the animals and the communities that rely on them.

Yaks ( Bos grunniens ), native to the Qinghai-Tibet Plateau, have evolved extraordinary physiological resilience to chronic hypoxia, cold, and nutritional scarcity. However, the integrated metabolic and microbial mechanisms underlying these adaptations remain poorly defined. Here, a comprehensive multi-omics analysis was performed on thirty grazing heifer yaks (2.5 years old) from three altitudes—3,600 m (low altitude [LA]), 4,000 m (middle altitude [MA]), and 4,500 m (high altitude [HA])—to investigate how altitude affects host physiology, metabolism, and gut microbial ecology. Increasing altitude significantly reduced serum total protein, globulin, blood urea nitrogen, and alkaline phosphatase, indicating suppressed anabolic metabolism and nitrogen-sparing strategies. Antioxidant capacity (total superoxide dismutase, total antioxidant capacity) and pro-inflammatory cytokines (interleukin-2 [IL-2], IL-6, tumor necrosis factor-α, interferon-γ) increased ( P < 0.05), while glutathione peroxidase, IL-4, IL-10, growth hormone, insulin-like growth factor-1, and growth hormone-releasing hormone declined ( P < 0.05), reflecting energy reallocation from growth toward antioxidation and immune maintenance under hypoxia. Plasma metabolomics revealed distinct altitude-dependent reprogramming, with enrichment of retinol metabolism at 4,000 m and α-linolenic acid metabolism, tricarboxylic acid (TCA) cycle, and branched-chain amino acid biosynthesis at 4,500 m. These pathways link lipid remodeling, oxidative balance, and oxygen utilization. The gut microbiota displayed altitude-specific shifts, characterized by enrichment of Christensenellaceae_R-7_group and Monoglobus and reduced UCG-005 and Rikenellaceae_RC9_gut_group , accompanied by lower fecal volatile fatty acids ( P < 0.05). Correlation analyses confirmed tight associations between fermentative taxa and volatile fatty acids production. Collectively, our results establish a serum–metabolome–microbiota axis as a central mechanism supporting yak adaptation to high altitude. IMPORTANCE: This study demonstrates that the gut microbiota plays a crucial role in how yaks adapt to high-altitude hypoxia. Rising altitude not only alters the composition of gut microbes but also shifts their metabolic activity toward improving fermentation efficiency and antioxidant capacity. These microbial changes are closely linked with host metabolism, forming a coordinated serum–metabolome–microbiota network that helps maintain energy balance and immune stability when oxygen is limited. The enrichment of retinol and α-linolenic acid metabolism as altitude-responsive pathways further highlights the metabolic interplay between host and microbes in supporting physiological resilience. Overall, our findings show that microbial flexibility and metabolic cooperation are key factors enabling ruminants to survive in extreme environments, providing a scientific basis for microbiome-informed strategies to enhance yak health and productivity on the Qinghai-Tibet Plateau.

High-altitude grazing animals are continuously exposed to strong wind and low temperature, which challenge physiological homeostasis and energy metabolism. Improving living conditions and nutritional supplementation are two commonly used strategies. In this study, sixty 7-month-old Gangba sheep (initial body weight (BW) 21.00 ± 1.90 kg) were allocated to a 42-day trial with four groups (open-air sheepfold, mobile sheepfold, open-air sheepfold + supplementary feeding, mobile sheepfold + supplementary feeding) to investigate their effects on growth performance, serum parameters and gut microbiota in naturally grazing Gangba sheep. Mobile sheepfolds increased the temperature–humidity index (THI) and reducing the wind chill index (WCI) (p < 0.05). The sheep with mobile sheepfold showed higher serum total antioxidant capacity and lower levels of heat shock proteins HSP70 and HSP90 (p < 0.05), indicating alleviated stress. Supplementary feeding markedly increased final BW and average daily gain (p < 0.05). The interaction between sheepfold type and feeding supplementation showed increasing IgA levels in the open-air sheepfold with supplementary feeding group and increasing IL-4 levels in the mobile sheepfold with supplementary feeding group, while TNF-α concentrations were reduced in all three treatment groups (p < 0.05). Meanwhile, KB and FFAs were increased in the open-air sheepfold with supplementary feeding group but decreased in the mobile sheepfold with supplementary feeding group (p < 0.05). The mobile sheepfold also increased the Bacillota-to-Bacteroidota ratio, suggesting improved microbial community structure. Functional predictions showed enrichment of reductive acetogenesis and reduction in aerobic chemoheterotrophy and sulfur-related respiration pathways (p < 0.05). Moreover, key microbial genera were significantly correlated with THI and WCI (p < 0.05). Collectively, these results demonstrated that mobile sheepfold together with feeding supplementation improve stress responses, serum immune and lipid metabolic indicators, and potentially altered gut microbial composition and function, providing insights into host–microbiota interaction in extreme high-altitude environments.

Objective: This study investigated the effects of chemically protected sodium butyrate (CSB) on growth performance, serum indicators, rumen fermentation parameters, and microbial communities in Gangba sheep.Methods: Twenty-four healthy 5-month-old male Gangba sheep with an initial body weight of 19.54±1.04 kg were randomly assigned to four groups and fed diets containing 0, 1.0, 5.0, and 10.0 g/kg CSB for 74 days. After a 14-day adaptation period, the daily feed intake of Gangba sheep was measured. Fecal samples were collected during the last 7 days of the trial, and serum and rumen fluid were sampled on the final day.Results: CSB improved final body weight, average daily dry matter intake, and average daily gain while reducing the feed conversion ratio of Gangba sheep (p<0.05). In addition, CSB improved the apparent digestibility of crude protein, dry matter, and neutral detergent fiber (p<0.05). Furthermore, CSB increased serum immunoglobulin G levels while decreasing tumor necrosis factor-α levels (p<0.05). Meanwhile, CSB increased serum growth hormone-releasing hormone levels (p<0.05). Furthermore, CSB increased rumen fluid pH and concentrations of ammonia nitrogen, acetic acid, iso-butyric acid, butyric acid, and total volatile fatty acids, as well as activities of lipase and butyrate kinase (p<0.05). Besides, CSB enhanced the rumen microbiota structure by increasing the relative abundance of Fibrobacter, unclassified Oscillospiraceae, and Ruminococcus.Conclusion: CSB improved immunological and hormone indicators, enhanced the rumen ecological environment, and increased feed digestibility and utilization, thereby promoting the growth of Gangba sheep. It is recommended to use a dosage of 5.0 g/kg dry matter for optimal growth performance and health benefits.