Abstract #433

# 433
Detection and management of pregnancy loss in a cow herd.
Ky G. Pohler*1, Michael F. Smith2, Jon A. Green2, Jose L. M. Vasconcelos3, 1Department of Animal Science, University of Tennessee, Knoxville, TN, 2Division of Animal Sciences, University of Missouri, Columbia, MO, 3Departamento de Produção Animal, Faculdade de MedicinaVeterinária e Zootecnia, UNESP, Botucatu, São Paulo, Brazil.

Reproductive wastage is a major contributor to the overall efficiency of a cattle operation. Management issues, cow or bull infertility, heat stress, and embryonic mortality are all contributing factors to reproductive inefficiency. Minimizing reproductive inefficiency, specifically embryonic mortality (EM) is vital. Embryonic mortality is generally considered to be the primary factor limiting pregnancy rates in cattle and occurs early (<d 28) or late (≥d 28) during gestation (d 0 = estrus). In cattle, the incidence of early EM is approximately 25% and the incidence of late EM is varied, approximately 3.2 to 42.7%. Significant effort has been directed toward understanding the mechanisms resulting in early EM; however, relatively little is known about the causes or mechanisms associated with late EM, most of which occurs around the time of placentation. To understand the mechanisms associated with reproductive loss around these time periods, specific markers must be characterized to help identify pregnancies that lead to success or failure. Extracellular microRNAs have been a recent area of biomarker discovery and based on recent evidence seem to be a promising target for an embryonic viability biomarker. Additionally, binucleate trophoblast cells constitute 15–20% of the ruminant placenta trophoblast population, appear around d 19–20 of gestation in cattle and secrete pregnancy associated glycoproteins (PAGs) along with other products in to the circulation. Bovine PAGs are commonly used to diagnose pregnancy success in cattle and have recently been reported to be a potential marker of late embryonic mortality in dairy and beef cattle. Using predicative value analysis, we have identified circulating concentrations of PAG that are 95% accurate in predicting EM at d 28 of gestation. This talk will highlight some of the work our group is focusing on to detect pregnancy loss during these pivotal periods of pregnancy loss and potential management aspects to mitigate reproductive inefficiency. This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2017–67015–26457 from the USDA National Institute of Food and Agriculture.

Key Words: cattle, pregnancy, placenta