Luteal color doppler ultrasonography and pregnancy-associated glycoproteins as early pregnancy diagnostic tools and predictors of pregnancy loss in Bos taurus postpartum beef cows.

Abstract

The objective of this study was to evaluate the use of luteal color doppler (CD) ultrasonography and plasma concentrations of pregnancy-associated glycoproteins (PAG) for early pregnancy diagnosis in Bos taurus beef cows. Additionally, CD and PAG were evaluated as potential predictors of late embryonic/early fetal mortality (LEM). Postpartum beef cows (n = 212) were exposed to estrus synchronization followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate corpus luteum (CL) morphometries and blood perfusion. Moreover, blood samples were collected on days 25 and 29 to quantify circulating concentrations of PAG. Conventional ultrasonography on days 29 and 100 was utilized as the gold-standard method for pregnancy diagnosis. Cows that experienced pregnancy loss between days 29 and 100 were classified as LEM. Pregnant cows had larger and more vascularized CL compared with nonpregnant cows on days 20 and 22 (P < 0.001 for all response variables). Accuracy for CD on days 20 and 22 were 87% and 92%, respectively. Accuracy for PAG on days 25 and 29 were 84% and 99%, respectively. No false negative (FN) results were observed for CD on both days 20 and 22; however, there were 7.1% FN results for PAG on day 25. Cows that experienced LEM had decreased (P = 0.04) circulating PAG on day 29 of gestation compared with cows that maintained pregnancy; however, there were no differences in luteal blood perfusion on days 20 and 22 (P ≥ 0.53) or circulating PAG on day 25 (P = 0.46) between LEM cows and cows that maintained pregnancy. Sensitivity and specificity of PAG on day 29 as predictors of LEM were 83% and 77%, respectively. In conclusion, CD resulted in accurate pregnancy diagnosis in B. taurus beef cows on both days 20 and 22 of gestation, while having no FN results. Circulating concentrations of PAG were decreased in cows that experienced LEM; however, further research is required to utilize PAG as a predictor of LEM commercially.