My research centers on reproduction in the dairy cow. I focus on the two major stresses affecting reproduction and fertitliy of cows - environmental heat stress and pathogenic stress.
- Regarding heat stress, we characterized impairments of follicular and luteal functions related to steroidogeneis, attenuation of follicular dominance and other preovulatory follicle-related functions.
- Regarding subclinical, chronic mastitis, we found that 1/3 of mastitic cows exhibited delayed ovulation. This syndrome involves disruption of follicular steroidogeneis, low gene expression in theca and granulosa cells and low and delayed LH surge.
- Attepts to improve fertility of subclinical mastitic cows are currently examined.
- We found that small early antral follicles are susceptible to long-term, exposure to minimal doses of both Gram-positive and Gram-negative toxins, and the induced damage is then carried over to the preovulatory follicles, corresponding well with the long-term chronic nature of subclinical mastitis.
- We also found lack of association between clinical mastitic events and premature induction of luteal regression, suggesting that the main cause of low fertility caused by E. coli mastitis post-AI is directed at the embryo rather than the corpus luteum.