A horse’s gut is a complex ecosystem that hosts a variety of microorganisms that play a critical role in digesting the fibrous diets that horses eat. Among the most important microorganisms are fibrolytic bacteria, which are essential for breaking down cellulose and hemicellulose in plant cell walls into nutrients that the horse can absorb. These bacteria are necessary for horses to obtain energy from their primary food sources, such as hay and grass.
However, foals are not born with these vital bacteria in their gastrointestinal tract. These microorganisms colonize the gut, a critical process that begins early in a foal’s life. As a study from the University of Kentucky’s Martin-Gatton College of Agriculture, Food and Environment published in MDPI Animals shows, one of the natural behaviors that enables this process is coprophagy, in which foals eat their mothers’ feces.
“Identifying the relationship between coprophagy and the establishment of fiber-digesting bacteria in the foal is an exciting step that adds another piece of the puzzle to understanding the foal’s microbiota and some of the factors that influence it,” said lead author Morgan Pyles, lecturer in equine science at the University of Minnesota Crookst and former PhD student in the UK Department of Animal and Food Sciences. “Some of our other research aimed to investigate the composition and yield of mare’s milk. A better understanding of these factors, such as coprophagy and milk composition, is important for developing management strategies for broodmares and also for rearing orphaned foals.”
Coprophagy may sound alarming at first, but it is a behavior seen in many animals and serves an important purpose. For foals, eating their mother’s feces is a way to ingest beneficial microbes they need to boost their gut ecosystem. The study focused specifically on how this behavior helps establish fibrolytic bacteria in the foal’s gastrointestinal tract.
The researchers used an innovative approach to confirm that the foals were engaging in coprophagia. They fed the mares chromium oxide, which is not digested or absorbed by the body and thus passes directly through the gastrointestinal tract. The presence of this marker in the foals’ feces directly confirmed the occurrence of coprophagia.
This bacterial colonization is of crucial importance for the foals when they transition to a diet that includes solid food as well as mother’s milk.
The study found a strong link between coprophagy and the colonization of fibrolytic bacteria in the foals’ gastrointestinal tract. This bacterial colonization is critical for the foals as they transition to a diet that includes solid foods in addition to their mother’s milk. This process represents a critical milestone in improving their digestive abilities and allows them to effectively extract nutrients from fibrous plant material.
These findings have practical implications for the care of foals. They highlight the importance of natural behaviours such as coprophagia for the healthy development of the horse’s gastrointestinal tract. This could influence how breeders and caregivers manage young horses and ensure they can display these behaviours, which in turn supports their health and growth.
“We also know from research in other species that the gastrointestinal microbiome plays a role in protecting the host from pathogens,” said co-author and professor in the Department of Animal and Food Sciences Laurie Lawrence. “We hope that by better understanding the normal colonization process in newborn foals, we will also learn more about best management practices for preventing neonatal gastrointestinal diseases such as diarrhea.”
Understanding the natural processes that contribute to the development of the gut microbiome in foals will inform equine care and enrich the general knowledge of microbial colonization in mammals, highlighting the complex host-microbe connections and revealing the advanced strategies animals have evolved to create and maintain a healthy gut microbiome.
