Comparative Analysis of Gut Microbiome, Metabolome and Meat Quality Among Chinese Steppe Red Cattle, Simmental Hybrid Cattle and Yanhuang Cattle.

Breed is a major source of variation in beef quality, yet how differences in rumen microbial communities relate to metabolic profiles and meat quality across breeds remains unclear. This study compared growth performance, meat quality traits, rumen microbiota, and rumen metabolomic profiles of Chinese steppe red cattle (CR), Yanhuang cattle (YH), and Simmental hybrid cattle (SH). The results showed that SH cattle had better performance in some growth-related traits. In contrast, YH and CR cattle exhibited better meat quality, with higher marbling scores, lower drip loss and shear force, and higher levels of several unsaturated fatty acids. Significant differences in individual amino acid contents were also observed among breeds, and SH cattle showed higher levels of some amino acids. Microbial analysis showed that CR and YH cattle had higher rumen microbial richness and diversity than SH cattle, with differences in microbial community composition among breeds. A total of 2425 metabolites were annotated by metabolomic analysis. The differential metabolites were mainly involved in lipid metabolism, amino acid metabolism, carbon metabolism, and energy metabolism pathways. Correlation analysis further revealed relationships between specific rumen microorganisms and metabolites related to meat quality traits.