Response of rumen fermentation and microbiota to high-energy diet in fattening sheep

Abstract

Abstract In mutton sheep production, higher dietary energy is often used to achieve better animal performance. Whereas, changing the diet formula will affect rumen fermentation and microbiota of ruminants. In this study, we investigated the effect of dietary energy on rumen fermentation and ruminal microbiota in fattening sheep. Fifteen 2-month-old white-headed Suffolk sheep (♂) × Hu sheep (♀) crossbred lambs were randomly divided into 3 treatments: 8.67 MJ/kg (LE, n=5), 10.38MJ/kg (CON, n=5), and 12.31 MJ/kg (HE, n=5) based on the dietary energy of feeds fed. After 70 days of feeding, sheep were slaughtered, and the ruminal fluids were collected and analyzed to determine fermentation parameters, microbiota was determined using metagenomics sequencing. We found that there was no effect on the microbial cell protein (MCP) and butyric acid concentration was significantly high in the HE group. Metagenomic sequencing revealed that ACE and Chao indexes of the HE group were significantly decreased. Among the major classified taxa, 4 genera across all the kingdoms differed in relative abundance among the three dietary energy levels. Correlation analysis revealed that the relative abundances of Prevotella_brevis, Succiniclasticum_ruminis, Prevotellace-ae_bacterium, andLachnospiraceae_bacterium were significantly correlated with rumen fermentation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis further showed high-energy diet increased lipid metabolism. The expression of the Carbohydrate Active enzymes (CAZy) gene indicated which participates in energy metabolism increased, but those which regulate plant cell wall degradation decreased in the HE group. These results suggest that a high-energy diet had limited influence on the rumen fermentation pattern. Whereas, a high-energy diet changes rumen microbiota composition which leading microbial lipid metabolism enhanced and crude fiber's metabolism capacities weakened. Our results provide scientific evidence for fattening sheep production.