The core faecal bacterial microbiome of Irish Thoroughbred racehorses.

UNLABELLED: In this study, we characterized the gut microbiota in six healthy Irish thoroughbred racehorses and showed it to be dominated by the phyla Firmicutes, Bacteroidetes, Proteobacteria, Verrucomicrobia, Actinobacteria, Euryarchaeota, Fibrobacteres and Spirochaetes. Moreover, all the horses harboured Clostridium, Fibrobacter, Faecalibacterium, Ruminococcus, Eubacterium, Oscillospira, Blautia Anaerotruncus, Coprococcus, Treponema and Lactobacillus spp. Notwithstanding the sample size, it was noteworthy that the core microbiota species assignments identified Fibrobacter succinogenes, Eubacterium coprostanoligenes, Eubacterium hallii, Eubacterium ruminantium, Oscillospira guillermondii, Sporobacter termiditis, Lactobacillus equicursoris, Treponema parvum and Treponema porcinum in all the horses. This is the first study of the faecal microbiota in the Irish thoroughbred racehorse, a significant competitor in the global bloodstock industry. The information gathered in this pilot study provides a foundation for veterinarians and other equine health-associated professionals to begin to analyse the microbiome of performance of racehorses. This study and subsequent work may lead to alternate dietary approaches aimed at minimizing the risk of microbiota-related dysbiosis in these performance animals. SIGNIFICANCE AND IMPACT OF THE STUDY: Although Irish thoroughbreds are used nationally and internationally as performance animals, very little is known about the core faecal microbiota of these animals. This is the first study to characterize the bacterial microbiota present in the Irish thoroughbred racehorse faeces and elucidate a core microbiome irrespective of diet, animal management and geographical location.