The effects of withholding feed for 24 hours on the equine faecal bacteria

The objective of this study was to determine the effect of withholding feed for 24 hours on the equine fecal bacteria. This study was an experimental, randomized, cross over design. Eight mares were assigned to (1) fed or (2) feed withheld groups. Fecal samples were collected from the rectum every 6 hours for 24 hours prior to study commencement, every 2 hours for 36 hours during and after the 24-hour feed withholding period, and every 6 hours for 24 hours after study completion. After 2 weeks, mares were assigned to the alternate group and the study repeated. Sample collection times were categorized as fed, early withheld, late withheld, early refed, and late refed and were compared between groups. Fecal bacterial genomic DNA was extracted, PCR- amplified, sequenced and analyzed. Species richness and Shannon diversity (alpha diversity) were measured. The extent of the relationship between bacterial communities were quantified, visualized using principal coordinate analysis (PCoA, beta diversity), and analyzed using PERMANOVA. Level of significance P<.05. Withholding feed significantly decreased species richness and Shannon diversity compared to fed horses during the late withheld and early refed times. Horses having feed withheld had a distinct bacterial population during the late withheld and early refed time points compared to fed horses. Withholding feed has a significant effect on fecal bacterial microbiota diversity and composition.