Effects of acute heat stress on intestinal microbiota in grow-finishing pigs, and associations with feed intake and serum profile.

Abstract

This study was conducted to assess the effects of acute heat stress (HS) on intestinal microbiota, and the associations with the changes in feed intake (FI) and serum profile. Twenty four individually housed pigs (Duroc×Large White×Landrace, 30±1kg body weight) were randomly assigned to receive one of three treatments (8 pigs/treatment): (i) thermal neutral (TN) conditions (25±1°C), (ii) HS conditions (35±1°C), (iii) pair-feeding (PF) with HS under TN conditions. After 24-h treatment, pigs were monitored to assess FI, and samples of serum and faeces were collected to investigate serum profile, microbial composition and short chain fatty acids (SCFAs). The results showed that HS decreased (P<0·05) FI compared with the TN group. Compared with TN group, HS changed the serum profile by affecting biochemical parameters and hormones related with energy metabolism and stress response; immune indicators were also altered in HS group. Most of changes in serum profile were independent of FI reduction. Additionally, HS shifted the diversity and composition of faecal microbial community by increasing (P<0·05) Proteobacteria and decreasing (P<0·05) Bacteroidetes. Moreover, HS decreased (P<0·05) the concentrations of propionate, butyrate, valerate, iso-valerate and total SCFAs in faeces in an FI-independent manner. Furthermore, the Spearman correlation analysis implied that changes of serum profile have potential correlation with alterations of faecal microbiota and their SCFAs metabolites in acute HS-treated grow-finishing pigs. Metabolism disorders caused by 24-h acute HS associated with changes of faecal microbiota and their SCFAs metabolites in an FI-independent manner in grow-finishing pigs. These results give us a new insight of the intestinal damage caused by acute HS and the underlying mechanisms.