The establishment of fibrolytic bacteria in the foal gastrointestinal tract is related to the occurrence of coprophagy by foals

Authors: PYLES, M. B. - University Of Minnesota Crookston; AGBANA, M. R. - University Of Kentucky; HAYES, S. H. - University Of Kentucky; Flythe, Michael; LAWRENCE, L. M. - University Of Kentucky

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2023
Publication Date: 8/26/2023
Citation: Pyles, M., Agbana, M., Hayes, S., Flythe, M.D., Lawrence, L. 2023. The establishment of fibrolytic bacteria in the foal gastrointestinal tract is related to the occurrence of coprophagy by foals. Animals. 13(17):2718. https://doi.org/10.3390/ani13172718.
DOI: https://doi.org/10.3390/ani13172718

Interpretive Summary: Every day we are finding new functions performed by the beneficial bacteria and other microbiota in the gastrointestinal tract. Beneficial gut bacteria are especially important for herbivorous animals, like horses, that need to get energy from fiber that cannot be digested by the ordinary enzymes of mammals. The fiber-degrading, or fibrolytic, bacteria digest tough plant fiber and allow the horse to get energy from it. Our previous research showed that bacteria begin to colonize a newborn foal on the first day of life and the gut microbiota quickly become similar to its mother. However, it was not clear how a foal acquired the important fibrolytic bacteria. Foals engage in a behavior called coprophagy, i.e., they eat the feces of their mother. We added an indigestible marker to the mother's feed. The marker came out in the mother's feces. When the feces were eaten by the foal, the marker would then show up in the foal's feces. All the foals began coprophagy between 3 and 7 days of life. When the marker showed up in the foal feces, fibrolytic bacteria that utilize the fiber, cellulose, were also detected. These results show that coprophagy is an early source for foals to receive both fiber and the beneficial bacteria they need to use the fiber. It is an important example of the value of allowing domestic animals to engage in their natural behaviors.

Technical Abstract: 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.