Research at the OSU Repro Lab currently focuses on three main pillars: 1) mechanisms regulating ovarian follicle development; 2) physiology of pregnancy maintenance beyond the time of classical maternal recognition of pregnancy in ruminants; and 3) on-farm technology for identification of reproductive processes and behaviors. The research approaches include investigation from a basic physiological perspective and is coupled with translation of the acquired knowledge into new or improved reproductive management strategies for both beef and dairy cattle.
Ovarian follicle development
Selection of a single follicle from a cohort of growing follicles is a unique biological process in female reproductive function in monovular species (e.g., cattle, humans, horses), and understanding these processes are integral in effectively conducting many reproductive techniques. Follicle growth and the number of follicles from which there is ovulation are regulated by precise control of endocrine, paracrine, and autocrine mechanisms. Understanding of the physiological processes involved in ovarian follicle recruitment, development and selection is very important for the design of efficacious assisted reproductive technologies as well as prevention of undesirable outcomes such as twinning. Our lab focuses on investigating the physiological mechanisms involved in follicle dynamics and the control of ovarian function that ultimately result in development and optimization of reproductive management strategies for fixed time artificial insemination (FTAI); ovarian superstimulation of follicular development for in vivo or in vitro embryo production and fixed time embryo transfer (FTET) programs. The approach utilized in our laboratory includes detailed characterization of physiological processes to understand the biology of ovarian follicle development as well as the implementation of large-scale field studies for the evaluation of reproductive management strategies for dairy and beef production.
Pregnancy maintenance beyond classical maternal recognition of pregnancy
Pregnancy loss, defined as failure of an established pregnancy to progress beyond a precise stage of pregnancy, is an important factor contributing to reproductive inefficiencies in both beef and dairy cattle operations. The traditionally accepted maternal recognition of pregnancy occurs within the first month of pregnancy and is the process by which a developing embryo signals its presence to the dam and allows for maintenance of pregnancy. Little is known, however, about the mechanisms maintaining pregnancy beyond the first month. Utilization of some reproductive techniques is associated with an increase in pregnancy loss during the second month of the gestational period highlighting the importance of this period. The inability to accurately predict when pregnancy losses will occur is a significant challenge for conducting research focused in this area. As a result, we have developed an in vivo model for induced pregnancy loss in cattle that allow us to characterize the ovarian, uterine, and endocrine characteristics of the dichotomy between pregnancy maintenance or pregnancy loss. The results from our research in this area are the foundation for future development of physiologically-based strategies for cattle producers to: 1) mitigate pregnancy losses occurring during the second month of gestation and 2) manage those in which pregnancy loss has occurred for prompt resumption of estrous cyclicity and rebreeding.
On-animal sensors for bull reproductive performance
Significant advances have been made to reproductive technologies such as artificial insemination; however, in most beef cattle enterprises there is a reliance on the use of bulls for natural mating and, thus, mating efficacy is a primary determinant of reproductive success and enterprise profitability. Mating efficiency is affected by bull libido as well as occurrence of breeding impediments, such as lameness. On-animal sensors such as accelerometers and GPS trackers allow for remote and real-time monitoring of animal behaviors, thus we have begun to utilize them to identify behaviors in bulls associated with libido and the occurrence of breeding impediments, ultimately to improve reproductive management of beef cattle. For this purpose, we have established a collaboration with Dr. Trotter from Central Queensland University, Australia.
