The equine gastrointestinal microbiome: impacts of weight-loss

• Published in: BMC veterinary research 2020-03, Vol.16 (1), p.78-78, Article 78
• Main Authors: Morrison, Philippa K, Newbold, Charles J, Jones, Eleanor, Worgan, Hilary J, Grove-White, Dai H, Dugdale, Alexandra H, Barfoot, Clare, Harris, Patricia A, Argo, Caroline McGregor
• Format: Article
• Language: English
• Subjects: acclimation; acetates; Analysis; Animal behavior; animal welfare; Animals; Apparent digestibility; Bacteria; bacterial communities; Biological markers; Body composition; Body fat; Body weight loss; community structure; Diet; dietary restriction; Dietary restrictions; Equine, equine obesity; Faecal microbiome; Fatty acids; feces; Firmicutes; Food and nutrition; Genes; Genetic research; hay; Health aspects; high-throughput nucleotide sequencing; Horses; Insulin; Insulin dysregulation; intestinal microorganisms; mares; Medical examination; Metabolism; microbiome; Microbiomes; Microbiota (Symbiotic organisms); Obesity; prediction; ribosomal RNA; RNA; Spirochaetes; Studies; Tenericutes; Time; Volatile fatty acid; Weight control; Weight loss; Welsh Mountain
• ISSN: 1746-6148; 1746-6148
• DOI: 10.1186/s12917-020-02295-6

Obesity is an important equine welfare issue. Whilst dietary restriction is the most effective weight-loss tool, individual animals range in their weight-loss propensity. Gastrointestinal-derived bacteria play a fundamental role in host-health and have been associated with obesity and weight-loss in other species. This study evaluated the faecal microbiome (next-generation sequencing of 16S rRNA genes) of 15 obese Welsh Mountain pony mares, in the same 11-week period across 2 years (n = 8 Year 1; n = 7 Year 2). Following a 4-week acclimation period (pre-diet phase) during which time individuals were fed the same hay to maintenance (2% body mass (BM) as daily dry matter (DM) intake), animals underwent a 7-week period of dietary restriction (1% BM hay as daily DM intake). Faeces were sampled on the final 3 days of the pre-diet phase and the final 3 days of the dietary restriction phase. Bacterial communities were determined using Next Generation Sequencing of amplified V1-V2 hypervariable regions of bacterial 16S rRNA. Losses in body mass ranged from 7.11 to 11.59%. Changes in the faecal microbiome composition following weight-loss included a reduction in the relative abundance of Firmicutes and Tenericutes and a reduction in indices of bacterial diversity. Pre-diet diversity was negatively associated with weight-loss. Pre-diet faecal acetate concentration was a strong predictor of subsequent weight-loss and negatively associated with Sphaerochaeta (Spirochaetes phylum) abundance. When animals were divided into 3 groups (high, mid, low) based overall weight loss, pre-diet bacterial community structure was found to have the greatest divergence between the high and low weight-loss groups (R = 0.67, p