Supplemental feeding of yeast cell wall promotes growth of Tibetan sheep by altering rumen fermentation and improving rumen microbiota and liver metabolism

Abstract Background The prolonged cold season on the Qinghai-Tibet Plateau poses substantial challenges for most animals, including limited access to natural pasture, reduced appetite, and subsequent weight loss. The polysaccharides that are contained in yeast cell wall (YCW) act as prebiotics, promoting the action and development of beneficial gut microbiota while inhibiting the proliferation of pathogens, thereby maintaining normal gastrointestinal function in animals. Methods This research aimed to examine how incorporating yeast cell wall (YCW) into the diet influences rumen fermentation, the composition of microbiota, and liver metabolism in Tibetan sheep. A total of 30 one-year-old Tibetan sheep, with an mean weight of 30.51 ± 7.07 kg, was randomly assigned to groups: a control group and a supplementation of 0.3% YCW group. Each group consisted of 15 sheep. The experimental period lasted for 98 days. Results The research showed that the addition of YCW increased Dry matter digestibility and average daily gain (ADG) of Tibetan sheep significantly ( P < 0.05); the concentrations of propionic acid, acetic acid, total volatile fatty acids, and ammonia nitrogen in the rumen were significantly increased ( P < 0.05); In the liver, the mRNA expression of genes associated with gluconeogenesis, including Glucose-6-phosphatase, catalytic subunit (G6PC), Phosphoenolpyruvate carboxykinase 1(PEPCK1), and Fructose-1,6-bisphosphatase (FBP), were significantly increased following YCW supplementation ( P < 0.05); the mRNA expression level of Sterol regulatory element-binding protein 1c (SREBP1c), which is involved in lipid metabolism, was significantly decreased ( P < 0.05); The inclusion of YCW in the diet reduced the relative abundance of Desulfobacterota and Firmicutes significantly, and increased Prevotella ’s abundance significantly in the rumen ( P < 0.05). Liver metabolites were substantially enriched in the glycerolipid metabolism, glycolysis/gluconeogenesis, and the AMP-activated protein kinase (AMPK) signaling pathway ( P < 0.05). Conclusions YCW supplementation in feed may advance the growth and gain of Tibetan sheep and improve gluconeogenesis. This effect may be ascribed to modifications in the rumen microbiota facilitating propionic acid fermentation, subsequently regulating liver lipid metabolism. Graphical Abstract