Relationships between rumen microbes, short-chain fatty acids, and markers of white adipose tissue browning during the cold season in grazing Mongolian sheep (Ovisaries)

Abstract

Mongolian sheep are characteristically cold-tolerant and they partially depend on seasonal browning of white adipose tissue (WAT) to acclimate to cold environments. The present work aimed to examine the rumen microbes, rumen fermentation profile, and relationships between the rumen microbiota, short-chain fatty acids (SCFAs), and markers of WAT browning and are thus conducive to exploring the plateau environment adaptability of Mongolian sheep in the cold season. A comparative analysis of the rumen microbes and SCFAs in the cold and warm seasons was conducted. Rumen microbes were analyzed using Illumina sequencing of the 16S rRNA gene. Ruminal SCFAs were determined by gas chromatography. Spearman's correlation test was used to determine the relationships between the rumen microbiota, SCFAs, and markers of WAT browning. Microbial 16S rRNA sequencing revealed a marked shift in rumen microbiota composition between the two seasons, and the bacteria were characterized by increased levels of the Actinobacteria and genera Christensenellaceae R-7 group, Ruminococcaceae UCG-011, Rikenellaceae RC9 gut group, Papillibacter, and Butyrivibrio 2 and reduced levels of Prevotella 1 and Ruminococcaceae UCG-014 in the cold season (P<0.05). Furthermore, the concentrations of SCFAs such as acetate and butyrate were significantly increased in the cold season (P<0.001 and P<0.05, respectively). Correlation analysis demonstrated that the relative abundances of the Actinobacteria and the genera Christensenellaceae R-7 group, Butyrivibrio 2, Ruminococcaceae UCG-002, and Ruminococcaceae UCG-011, identified as members of the Christensenellaceae, Lachnospiraceae, and Ruminococcaceae families (all within Firmicutes), were positively correlated with markers of browning in either retroperitoneal WAT or perirenal WAT, and acetate was positively correlated with Ruminococcaceae UCG-011 and Butyrivibrio 2 and markers of browning in either retroperitoneal WAT or perirenal WAT. Overall, there are distinct relationships between the rumen microbiota, ruminal SCFAs and markers of WAT browning during the cold season in grazing Mongolian sheep.

Keywords: Cold tolerant; Mongolian sheep (Ovis aries); Rumen microbiota; Seasonal acclimation; Short-chain fatty acids.