The equine gastrointestinal microbiome: Impacts of weight-loss

Philippa K. Morrison*, Charles J. Newbold, Eleanor Jones, Hilary J. Worgan, Dai H. Grove-White, Alexandra H. Dugdale, Clare Barfoot, Patricia A. Harris, Caroline McGregor Argo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (SciVal)
218 Downloads (Pure)


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 
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.
Original languageEnglish
Article number78
Pages (from-to)78
Number of pages18
JournalBMC Veterinary Research
Issue number1
Publication statusPublished - 04 Mar 2020


  • Research Article
  • Gastroenterology and nutrition
  • Equine, equine obesity
  • Weight-loss
  • Insulin dysregulation
  • Faecal microbiome
  • Apparent digestibility
  • Volatile fatty acid
  • Biomarkers
  • Diet/veterinary
  • Gastrointestinal Microbiome
  • Obesity/microbiology
  • Acetates/analysis
  • Animals
  • Horses/microbiology
  • Female
  • Feces/chemistry
  • Weight Loss/physiology
  • RNA, Ribosomal, 16S


Dive into the research topics of 'The equine gastrointestinal microbiome: Impacts of weight-loss'. Together they form a unique fingerprint.

Cite this