Interactions of rumen microbiota, and metabolites with meat quality-related genes to regulate meat quality and flavor of Tibetan sheep under nutrient stress in the cold season.

Abstract

The meat of Tibetan sheep has unique flavor, delicious taste and superior nutritional value. However, the change of grass will lead to a change in meat quality. This study aimed to explore the potential regulatory mechanism of microbial metabolites with respect to meat quality traits of Tibetan sheep under nutrient stress in the cold season. We determined and analyzed the longissimus dorsi quality, fatty acid composition, expression of genes and rumen microbial metabolites of Tibetan sheep in cold and warm seasons. The shear force was decreased (P < 0.05), the meat color a*24h value was increased (P < 0.05), and the contents of crude fat (EE) and protein (CP) were decreased in the cold season. Polyunsaturated fatty acids (PUFAs)-linoleic acid and docosahexaenoic acid (DHA) increased significantly in the cold season (P < 0.05). The expressions of meat quality genes MC4R, CAPN1, H-FABP and LPL were significantly higher in the warm season (P < 0.05), and the CAST gene was significantly expressed in the cold season (P < 0.01). The different microbial metabolites of Tibetan sheep in the cold and warm seasons were mainly involved in amino acid metabolism, lipid metabolism and digestive system pathway, and there was some correlation between microbiota and meat quality traits. There are similarities between microbial metabolites enriched in the lipid metabolism pathway and muscle metabolites. Under nutritional stress in the cold season, the muscle tenderness of Tibetan sheep was improved, and the fat deposition energy was weakened, but the levels of beneficial fatty acids were higher than those in the warm season, which was more conducive to healthy eating.