High-energy diet modify rumen microbial composition and microbial energy metabolism pattern in fattening sheep.

Higher dietary energy is often used to achieve better animal performance in mutton sheep production. Notably, changing the diet formula affects rumen fermentation and the 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 three treatments based on the dietary energy of the feeds fed: 8.67 MJ/kg (Low energy (LE); n = 5), 10.38 MJ/kg (standard energy (CON); n = 5), and 12.31 MJ/kg (high energy (HE); n = 5) groups. 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. Notably, the microbial cell protein (MCP) and butyric acid concentrations were significantly high in the HE group. Metagenomic sequencing revealed that ACE and Chao indexes of the HE group were significantly decreased. Four genera among the major classified taxa across all the kingdoms differed in relative abundance in the three dietary energy levels. The relative abundances of Prevotella_brevis, Succiniclasticum_ruminis, Prevotellace-ae_bacterium, and Lachnospiraceae_bacterium were significantly correlated with rumen fermentation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis further revealed that a high-energy diet increased lipid metabolism of microbiota. The Carbohydrate Active enzymes (CAZy) gene, which participates in energy metabolism, was upregulated, while genes regulating plant cell wall degradation were downregulated in the HE group. These results suggest that a high-energy diet had minimal influence on the rumen fermentation pattern but altered the composition of the rumen microbiota, enhancing microbial lipid metabolism and limiting crude fiber metabolism. The findings of this study provide scientific evidence of the effect of dietary energy on ruminant fermentation and fattening sheep production.

miR-27a Regulates Sheep Adipocyte Differentiation by Targeting CPT1B Gene.

MiRNAs are vital regulators and play a major role in cell differentiation, biological development, and disease occurrence. In recent years, many studies have found that miRNAs are involved in the proliferation and differentiation of adipocytes. The objective of this study was to evaluate the effect of miR-27a and its target gene CPT1B on ovine preadipocytes differentiation in Small-tailed Han sheep (Ovis aries). Down-regulation of miR-27a significantly promoted the production of lipid droplets, while overexpression of miR-27a led to a reduction in lipid droplet production. In addition, inhibition of miR-27a led to a significant increase in the expression of genes involved in lipid synthesis, including PPAR γ, SCD, LPL, and FABP4. Target Scan software predicted that CPT1B is a new potential target gene of miR-27a. Further experiments revealed that CPT1B gene expression and protein levels were negatively correlated with miR-27a expression. Overexpression of miR-27a led to a significant decrease in CPT1B mRNA levels and inhibited the accumulation of lipid droplets and vice versa. Moreover, overexpression of CPT1B promoted the synthesis of lipid droplets in ovine preadipocytes. Furthermore, luciferase reporter assays confirmed CPT1B to be a miR-27a direct target gene. This study confirmed that miR-27a increases the expression of genes related to lipid synthesis in ovine preadipocytes by targeting CPT1B, thereby promoting the synthesis of lipid droplets. The results of this study can be used to be exploited in devising novel approaches for improving the IMF content of sheep.