The Establishment of Fibrolytic Bacteria in the Foal Gastrointestinal Tract Is Related to the Occurrence of Coprophagy by Foals

SIMPLE SUMMARY: Horses rely on specific functional groups in the microbial community in their gastrointestinal tract to digest fiber-rich feedstuffs such as hay and pasture. The microbial community is not fully functional at birth but changes and develops with age. The factors directing the development of the microbial community in the foal are not well understood. The consumption of maternal feces, coprophagy, is part of the normal behavior in the foal and may contribute to microbial colonization. To investigate coprophagy in foals, mares were fed an indigestible marker that was excreted in their feces. When the foals consumed maternal feces, the marker was detected in the foal’s feces. The results suggest that coprophagy is important for the establishment of fibrolytic bacteria in the foals’ gastrointestinal tract. Maternal feces are rich in fiber and live microbes, providing both a prebiotic and a probiotic to the foal. ABSTRACT: The consumption of maternal feces (coprophagy) is commonly observed in healthy foals and is a proposed contributor to microbial colonization of the foal’s gastrointestinal tract (GIT). This study investigated the role of coprophagy in the establishment of fibrolytic bacteria in the foal GIT. Nine thoroughbred mares were dosed with chromic oxide, an indigestible marker, as a method to detect the occurrence of coprophagy by their foals. Foal fecal samples were collected from 12 h to 21 d after birth to measure chromic oxide and neutral detergent fiber (NDF) and to enumerate cellulolytic bacteria using culture-based techniques. Milk yield was estimated at 7 and 14 d postpartum. Coprophagy was detected as early as 3 d after birth and detected in all foals by 7 d of age. There were strong relationships between coprophagy and cellulolytic bacteria and NDF in foal feces at 7 d of age (r = 0.9703 and r = 0.7878, respectively; p < 0.05). Fecal NDF and chromic oxide concentrations were negatively related to milk yield (r = –0.8144 and r = –0.6966, respectively; p < 0.05), suggesting milk availability affected the incidence of coprophagy. Based on the relationships identified, maternal feces are an important source of fiber and live microbes for the foal, contributing to the development of the microbial community.