Theses and Dissertations


Riley Messman

Issuing Body

Mississippi State University


Lemley, Caleb

Committee Member

Larson, Jamie

Committee Member

Stone, Amanda

Committee Member

Paz, Henry

Date of Degree


Document Type

Graduate Thesis - Open Access


Animal and Dairy Science

Degree Name

Master of Science


College of Agriculture and Life Sciences


Department of Animal and Dairy Sciences


Most research evaluating the effects of the reproductive tract microbiota on reproductive performance has been done in humans, thus far. In bovids, reproductive microbiota research is not as advanced, with preliminary conclusions, not supported by contamination checks or repeatability. Our studies concluded that endogenous reproductive hormones, days of gestation, and pregnancy status does not change the overall vaginal microbiota composition. Although, the overall composition did not change there were species level differences. These differences could have implications in reproductive performance and fertility in heifers. Heifers that undergo nutrient restriction have similar vaginal microbiota to adequately fed heifers with no species differences. The most impactful finding is that exogenous supplementation of melatonin was associated with changes in the vaginal microbiota in Brangus heifers during late gestation. The implications of this finding are not yet clear, but to date, this is the first hormone, in bovids, determined to change the composition of the vaginal microbiota.