Grazing Practice Affect the Growth Performance, Meat Quality and Nutritional Composition and Fecal Microbiota of Fattening Yaks

Livestock grazing is the primary practice in alpine meadows, which is closely related to animal performance and ecosystem functions. This study aimed to evaluate the effects of grazing practice on the growth performance, meat nutritional composition and shelf life, and fecal nutrient and microbiota of yaks. Twenty-four male yaks (217.62 ± 5.74 kg) were randomly divided into 2 groups for a 60 d fattening experiment: grazing (G) group and grazing and supplementary feeding (GS) group. The yaks in the G group were grazed only on natural pastures, without any supplements. The yaks in the GS group were not only grazed on natural pastures, also supplemented with the concentrate mix based on the body weight after grazing. Supplementary feeding concentrate mix after grazing significantly increased the body weight (p < 0.01) and average daily gain (p < 0.01) of yaks. The results indicated that supplementary feeding reduced meat shear force (p = 0.04), increased the a* value (p < 0.01), the b* value (p = 0.04) and the ether extract content (p = 0.03), and extended the shelf life by 3.4 h. The total amino acid content increased (p < 0.01) and promoted the deposition of monounsaturated fatty acids (p < 0.01) and polyunsaturated fatty acids (p < 0.01). The output concentration of nitrogen in feces was increased (p = 0.04), and the 16S rRNA sequencing results showed that grazing with supplementary feeding significantly increased the relative abundance of key genera, including Alistipes, UCG-009, Tuzzerella, Family_XIII_UCG-001, and Erysipelatoclostridium, which are associated with nutrient absorption, fiber degradation, and metabolism. Post-grazing concentrate mix supplementation improved yak growth, meat quality, and shelf life, likely via enhanced amino acid and fatty acid deposition, nitrogen retention, and gut microbial shifts-offering new insights into nutrient metabolism and feeding strategies for high-altitude livestock.