Faecal Microbiome of the T horoughbred Racehorse and Its Response to Dietary Amylase Supplementation

Abstract

Introduction The horse has evolved to survive on a low-energy, high-fibre diet. The addition of starch, in the form of cereals, to the diet of racehorses to satisfy the high energy demands of extreme exercise has been identified as a risk factor for intestinal dysfunction. In this study we use 454 pyrosequencing of 16S rRNA genes to characterize the gut microbiome of 8 Thoroughbred (Tb) racehorses and study the response to dietary supplementation. Methods Faecal samples were collected from 8 Tb racehorses in training. A second sample was collected from all horses six weeks after commencement of twice daily dietary supplementation with an amylase-rich malt extract, designed to enhance pre-caecal digestion. Amplicons for the V1-V3 region of the 16S rDNA gene were multiplexed and sequenced on the 454 resulting in ?25,000 reads per sample. Differences in bacterial community structure were detected by linear discriminant analysis. Results Communities were composed of an equal balance between Bacteroidetes and Firmicutes with a ?5% contribution from other bacterial phyla. The number of observed operational taxonomic units sharing ≥97% nucleotide sequence in our racehorse population was 6000?8000. Horses showed no significant change in the number of OTUs observed after diet supplementation, but significant changes in the relative abundance of both Bacteroidetes and Firmicutes families were observed. Conclusions We demonstrated a highly diverse and complex faecal microbial community in Tb racehorses in the UK. Inter-horse variability is low amongst horses in the same training yard. We identified significant shifts in community profile following dietary supplementation and speculate that these may enhance intestinal health. Ethical Animal Research This study was conducted under the University of Liverpool research ethics approval: RETH000363. The informed consent of the trainer was obtained and all samples were obtained non-invasively. Sources of funding:?private donation. Competing interests:?none.