Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Animal and Food Sciences

First Advisor

Dr. Laurie Lawrence


The process of microbial colonization in the gastrointestinal tract of foals and the factors influencing this process are not well understood. The objectives were to determine the effect of starch source in pelleted concentrates in the maternal diet on select fecal bacterial groups in mares and their foals and to evaluate changes in these bacterial groups over time. Thoroughbred foals (n=19) were from dams fed one of two concentrates: an oat-based (OB) or corn and wheat middling-based (CWB) pelleted concentrate. Fecal samples were collected from mares at 324 d of gestation, pre-foaling, 1 d, 14 d, and 28 d after parturition and from foals at 1 d, 4 d, 14 d, and 28 d after birth. Total starch-utilizing bacteria (TSU) and lactobacilli increased with age and were more numerous in the feces of OB foals compared to CWB foals at 1 d and 4 d of age (P < 0.05). Foal cellulolytic bacteria were not influenced by maternal diet (P > 0.05) and increased with age (P < 0.05). There was no influence of starch source on fecal bacteria in mares (P > 0.05). Lactobacilli and cellulolytic bacteria in mares decreased 1 d postpartum (P < 0.05) whereas TSU remained stable over time (P > 0.05). These results indicated that microbial colonization of the foal’s gastrointestinal tract begins soon after birth and some bacteria may be influenced by maternal diet. Furthermore, the hindgut microbiota of broodmares may be altered by parturition.

Digital Object Identifier (DOI)