Molecular diversity of the equine caecal microbiota and its correlation to postprandial fermentation metabolites: A preliminary approach

Abstract

In this work we address the short-term postprandial dynamic changes in the equine caecal microbial composition and the microbial fermentation metabolites in the caecum. Samples were collected every half hour for 8.5 hours postfeeding from two horses on two consecutive days. The caecal content of volatile fatty acids (VFAs), lactate, and ammonia (NH₃N), as well as microbiota composition and pH were analyzed. Mixed Sangers sequences generated from universal polymerase chain reaction (PCR)-amplified 16S rRNA gene were used to analyze the microbiota composition. Three main phylogroups were identified and classified as Clostridium cluster XIVa, Clostridium cluster III, and lactic acid bacteria. Furthermore, we found that the composition of the caecal microbiota was closely associated with the VFA profile. Our main findings were that short-term microbial fluctuations occur in healthy hindgut fermenting horses as a response to feed intake.

Keywords:

• 16S rDNA
• caecal postprandial dynamics
• microbiota
• volatile fatty acids
• equine

Acknowledgments

We would like to thank Monica Sekelja for valuable methodological discussions and Signe Drømtorp for instructions regarding the practical work in the laboratory. Nofima is thanked for their financial support. Naja C. K. Hansen was supported by a PhD grant from The Norwegian University of Life Sciences, Ås, Norway.