The equine gastrointestinal microbiomeImpacts of weight-loss

Authors Organisations
  • Philippa K. Morrison(Author)
    Scotland's Rural College
  • Charles J. Newbold(Author)
    Scotland's Rural College
  • Eleanor Jones(Author)
  • Hilary Worgan(Author)
  • Dai H. Grove-White(Author)
    University of Liverpool
  • Alexandra H. Dugdale(Author)
    Chester Gates Veterinary Specialists
  • Clare Barfoot(Author)
    MARS Horsecare
  • Patricia A. Harris(Author)
    Waltham Petcare Science Institute
  • Caroline McGregor Argo(Author)
    Scotland's Rural College
Type Article
Original languageEnglish
Article number78
Number of pages18
JournalBMC Veterinary Research
Issue number1
Early online date04 Mar 2020
Publication statusE-pub ahead of print - 04 Mar 2020
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Abstract: Background: 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. Results: 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 <0.01), following PERMANOVA and ANOSIM analysis. Conclusions: Weight-loss in this group of ponies was associated with lower pre-diet faecal bacterial diversity and greater pre-diet acetate concentration. Overall, these data support a role for the faecal microbiome in weight-loss propensity in ponies and provide a baseline for research evaluating elements of the faecal microbiome in predicting weight-loss success in larger cohorts.


  • Research Article, Gastroenterology and nutrition, Equine, equine obesity, Weight-loss, Insulin dysregulation, Faecal microbiome, Apparent digestibility, Volatile fatty acid, Biomarkers