Effect of heat stress on growth performance, carcase characteristics, meat quality and rumen-muscle axis of Hu sheep

Abstract

This study aimed to investigate the effects of heat stress (HS) on growth performance, carcase characteristics and rumen-muscle axis of Hu sheep and to explore the underlying molecular mechanisms of the actions by establishing a heat-stressed Hu sheep. The results showed that HS significantly decreased growth performance and carcase characteristics, altered metabolic enzyme activities, and induced a shift in muscle energy metabolism towards a more glycolytic and less oxidative fibre type in the longissimus dorsi (LD) muscle (p < 0.05), thereby affecting the meat quality of Hu sheep. Furthermore, RNA-seq analysis of LD muscle found that HS down-regulated the expression of genes (ADIPOQ, ADRA2A, COL6A3, MYOC, PPARGC1A, etc.) involved in fat deposition and muscle development. 16S rDNA analyses of ruminal microbiome revealed that resist adverse environments-related Firmicutes, fatty acid synthesis-related Ruminococcaceae, Prevotellaceae, etc. were increased in the heat-stressed Hu sheep, and negatively correlated with genes involved in muscle development and lipid metabolism. However, energy metabolism-related Bacteroidetes and Tenericutes, and protein and carbohydrate cleavage-related Prevotella and Mollicutes were decreased in the heat-stressed Hu sheep and positively correlated with genes involved in muscle development and lipid metabolism. All together, these findings indicated that the rumen microbiota and gene expression profiles of muscle underwent responsive changes to HS, which impaired growth performance, carcase characteristics and meat quality in Hu sheep. Our findings provide valuable insights into the mechanisms underlying heat stress-induced effects in sheep, suggesting potential strategies for the prevention and control of HS as well as the development of new heat-resistant varieties in Hu sheep using molecular design breeding.