# Meat Quality Differences Between Ganan Tibetan Sheep and Tianzhu Tibetan Sheep Using Metabolomics and Rumen Microbiota Analyses

## TL;DR

This study explores how differences in rumen microbes between two Tibetan sheep breeds affect meat quality traits like fat content.

## Contribution

The study reveals distinct microbial associations with intramuscular and subcutaneous fat traits in Tibetan sheep.

## Key findings

- Higher fat content correlates with greater ruminal microbial species richness.
- Ruminococcus 1 abundance is positively linked to marbling score.
- Microbial taxa differ in their associations with intramuscular and subcutaneous fat traits.

## Abstract

The objective of this study was to investigate the relationships between ruminal microbial communities and carcass traits associated with adipose accumulation in two Tibetan sheep breeds—Gannan and Tianzhu. A total of twenty Tibetan sheep (ten from each breed) were slaughtered, and samples of ruminal contents along with carcass trait data were collected for analysis. Ruminal microbial DNA was analyzed by 16S rRNA gene sequencing, and correlations between microbial composition and carcass traits were examined using correlation analysis and one-way ANOVA. The results showed that marbling score (p = 0.001) and longissimus lipid content (p = 0.007) were positively correlated with the Chao1 richness index, indicating that individuals with higher intramuscular fat content had greater ruminal microbial species richness. At the phylum level, Rikenellaceae RC9 gut group, Ruminococcaceae NK4A214 group were negatively correlated (p ≤ 0.05) with the above fat traits, whereas the abundance of the bacterial family Ruminococcus 1 was positively correlated with marbling score (p = 0.002). Stratified analysis by marbling grade further revealed associations with microbial richness (p ≤ 0.063), diversity (p = 0.044), and Ruminococcus 1 abundance (p < 0.001). However, microbial metabolic pathway prediction showed no significant differences (p ≥ 0.05) between the high- and low-marbling groups. In addition, several microbial taxa were positively correlated (p ≤ 0.05) with rib fat thickness and yield grade. In summary, ruminal microbial composition was closely associated with variations in carcass fat traits. Notably, most of the bacterial taxa associated with intramuscular and subcutaneous fat deposition did not overlap, suggesting that microbial metabolites may regulate fat deposition by influencing distinct adipogenic pathways in the host.