238 Luteal Color Doppler Ultrasonography for Early Pregnancy Diagnosis in Postpartum Bos Taurus Beef Cows

The objective of this study was to evaluate the use of corpus luteum (CL) color doppler ultrasonography (CD) for early pregnancy diagnosis in Bos taurus beef cows and evaluate differences in CL blood perfusion among cows that experience late embryonic/early fetal mortality (LEM). Postpartum Bos taurus beef cows (n = 214) from three locations were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate CL morphometries and blood perfusion, respectively. Cows were considered non-pregnant when CL area was < 20 mm2 or estimated blood perfusion was ≤ 25%. Conventional ultrasonography on day 29 was utilized as the gold standard method. Pregnant cows had greater CL diameter, CL area, and CL volume when compared to non-pregnant cows on day 20 and 22 (P < 0.001; Table 1). Additionally, percentage of central, peripheral, and total luteal blood perfusion, as well as the respective blood perfusion scores were greater (P < 0.001) in pregnant compared with non-pregnant cows on both day 20 and 22. Sensitivity, specificity, positive predicted value (PPV), negative predicted value (NPV), and accuracy for the CD on day 20 were 100, 74, 81, 100, and 88%, respectively. Sensitivity, specificity, PPV, NPV, and accuracy for CD on day 22 were 100, 86, 89, 100, and 93%, respectively. Pairwise comparison of receiver operating characteristics curve analysis indicated no differences between CD on days 20 and 22 (P = 0.12). No differences in luteal blood perfusion were observed on day 20 or 22 among cows that maintained pregnancies compared with LEM cows (P ≥ 0.27). In conclusion, CD successfully detected most non-pregnant cows (81 and 89% on day 20 and 22, respectively) and false negative results were absent (NPV = 100%).