Markers of pregnancy: how early can we detect pregnancies in cattle usingpregnancy-associated glycoproteins (PAGs) and microRNAs?

S. T. Reese,M. C. Pereira,R. F. G. Peres,M. F. Smith,K. G. Pohler,J. L. M. Vasconcelos,T. W. Geary,J. A. Green,G. A. Perry

doi:10.21451/1984-3143-ar878

Abstract

Pregnancy detection has evolved over the last few decades and the importance of early pregnancy detection is critical to minimize the amount of time a cow spends not pregnant. Embryonic mortality (EM) is generally considered to be the primary factor limiting pregnancy rates in cattle and occurs early (<day 28) or late (≥ day 28) during gestation (day 0 = estrus). In cattle, the incidence of early EM is approximately 20 to 40% and the incidence of late EM is approximately 3.2 to 42.7%. Significant effort has been directed toward understanding the mechanisms resulting in early EM up to day 17; however, relatively little is known about the causes or mechanisms associated with EM after day 17. Based on work in these areas, numerous investigators are pursuing methods of early pregnancy or EM detection after day 17 of gestation. This review will highlight some of the technology and markers being used for early pregnancy detection and provide evidence for just how early pregnancy can be detected in the bovine. Advancements in early embryonic or pregnancy detection may lead to development of strategies to overcome early gestation losses.

Highlights

Pregnancy failure is extremely costly to the producer
This review will describe various methods of pregnancy diagnosis in cattle and research advancements that may allow for earlier detection of pregnancy
As the conceptus develops during gestation, fluid accumulates, and placentation advances, methods of pregnancy detection allow for manual transrectal palpation of the uterus per rectum and its contents

Summary

Introduction

Pregnancy failure is extremely costly to the producer. Lost revenue can be attributed to cost of feeding and managing nonpregnant cows, decreased weight of late born calves at sale time and a decreased calving percentage due to cows that lost pregnancy. In a study involving lactating dairy cows, pregnancy loss after 1 month of gestation cost producers an average of $555 (US) due to repeat breeding expenses, increased calving interval and increased probability of involuntary culling (De Vries, 2006). In beef cattle that have had pregnancy loss and manage to become pregnant to a subsequent breeding, there is still a significant amount of lost revenue from reduced weight of late born calves and decreased uniformity of the calf crop. Utilize pregnancy diagnosis via palpation or ultrasound, a number that has remained virtually unchanged since the 1997 survey (United States Department of Agriculture - USDA, 2010). The 2007 NAHMS Dairy survey reported 93% of operations perform pregnancy detection (USDA, 2009). Pregnancy diagnosis can identify open cows, help estimate calving dates, and help producers make culling decisions. This review will describe various methods of pregnancy diagnosis in cattle and research advancements that may allow for earlier detection of pregnancy

Established methods of pregnancy diagnosis

Findings

Conclusions