Date of Award:

5-2024

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

S. Clay Isom

Committee

S. Clay Isom

Committee

Aaron Thomas

Committee

Irina Polejaeva

Abstract

It is common practice in the livestock animal production industries to feed high levels of protein to maximize the yield of each animal in production. However, diets high in protein can cause decreased reproductive success within these animals. The causes behind this decrease are not fully understood. Increased dietary protein leads to increased levels of both ammonia and urea in the blood of the animal. These increased metabolite levels may be a possible explanation for the decline in reproductive success. The goal of this study is to identify how various levels of ammonia affect the function of bovine granulosa cells in vitro. The cells used for these experiments were harvested from abattoir-derived bovine ovaries. After the cells were established in culture, they were exposed to media containing 1 mM, 2 mM, 3 mM, 4 mM, 5 mM, 6 mM, and 7 mM ammonia for 24 hours. The cells were then evaluated for viability, proliferation rates, gene expression, cellular stress, and hormone production. There were significant changes in proliferation between the control and the 6mM ammonia group, and the control and the 7 mM ammonia group. There was also a significant impact on viability in the 7 mM ammonia group. Ten out of twenty-five genes involved in steroidogenesis, redox reactions, or solute transport from our analysis showed significant changes due to ammonia treatment. There were no significant changes in hormone production or reactive oxygen species in response to ammonia treatment. The levels of ammonia that induced the changes noted are above normal physiological levels but are achievable in vivo depending on the amounts of protein in an animal’s diet. This study shows that granulosa cells are in some ways impacted by varying levels of ammonia. Future studies will reveal how the changes to these granulosa cells under these conditions might impact the ovarian follicular microenvironment, subsequent oocyte maturation and embryo development, and reproductive performance in general.

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