Session: Physiology and Endocrinology I

236 - Factors Influencing Clearance of Pregnancy-associated Glycoproteins in Postpartum Beef Cattle

Friday, July 16, 2021

9:30 AM – 9:45 AM EST

Location: Kentucky International Convention Center (KICC), M109 & 110

Presenting Author(s)

Adalaide C. Kline

Graduate Student
South Dakota State University
Mission Hills, Kansas

PDF Slides and Audio

Author(s)

JW

Julie Walker

Extension Beef Specialist
South Dakota State University
Brookings, South Dakota
Taylor Andrews

Graduate Student
South Dakota State University
Brookings, South Dakota
Saulo Menegatti Zoca, PhD Candidate

Graduate Student
South Dakota State University
Brookings, South Dakota
Kaitlin M. Epperson, MS

Graduate Student
Texas A&M University
College Station, Texas
Lacey Quail, M.S.

Graduate Student
Texas A&M University
College Station, Texas
Jerica J J Rich, Ph.D.

Assistant Professor of Animal Science
Arkansas State University - College of Agriculture
Jonesboro, Arkansas
GP

George A. Perry

Texas A&M AgriLife Research, Overton
Overton, Texas
JR

Jim R. Rhoades

IDEXX
Westbrook, Maine

Blood pregnancy tests can determine pregnancy status in cattle; however, pregnancy-associated glycoproteins (PAGs) have a long half-life (80 to 100 d). If tested too soon after calving, false positive readings can occur due to elevated concentrations from the previous pregnancy. This study’s objective was to determine factors that impact clearance of PAGs in postpartum beef females. Blood samples were collected from postpartum Angus and Angus-cross females (primiparous n = 46 and multiparous n = 58); once a week for up to 14 weeks after calving (range of first to last sample 1-7 to 98-105 days postpartum; dpp). Serum was tested in duplicate using the IDEXX Alertys Pregnancy Test. Data were analyzed as a repeated measure using the MIXED procedure of SAS (9.4) with parity, calf sex (sex), days postpartum, and all interactions in the model. Data were analyzed using the REG procedure in SAS. There was a significant effect of dpp (P < 0.01) on PAG concentrations; however, PAG concentrations were not influenced by parity (P = 0.24), sex (P = 0.49), parity by dpp (P = 0.12), parity by sex (P = 0.65), sex by dpp (P = 0.37), or parity by sex by dpp (P = 0.99). Concentrations of PAGs rapidly decreased from d 0 to 50 postpartum and then continued to gradually decrease to d 100. Days postpartum accounted for 67.53% of the variation in PAG concentrations. Prior to 50 dpp, PAG concentrations were sufficiently elevated which resulted in false positive readings (S – N ≥ 0.3). In summary, concentrations of PAGs remained elevated after calving, but the clearance of PAGs were not impacted by parity or sex of the calf. Clearance of PAGs were significantly influenced by days postpartum. Additionally, using a blood pregnancy test prior to d 50 postpartum would increase the likelihood of false positive readings due to residual PAG concentrations from the previous pregnancy.