5 Early Pregnancy Diagnosis inbos Taurus beef Replacement Heifers Using Color Doppler Ultrasonography

Abstract

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 replacement heifers. Beef heifers (n = 183) from two 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. Heifers were considered non-pregnant when CL area was < 20 mm2 or estimated luteal blood perfusion was ≤ 25%. Conventional ultrasonography on day 29 was utilized to determine pregnancy status and considered the gold standard method for pregnancy diagnosis. Pregnant heifers had greater CL diameter, CL area, and CL volume when compared to non-pregnant heifers on days 20 and 22 (P < 0.001). 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 heifers on both day 20 and 22. Sensitivity, specificity, positive predicted value (PPV), negative predicted value (NPV), and accuracy for CD on day 20 were 100, 70, 86, 100, and 90, respectively. Sensitivity, specificity, PPV, NPV, and accuracy for CD on day 22 were 100, 76, 90, 100, and 92, respectively. Pairwise comparison of receiver operating characteristics curve analysis indicated no differences (P = 0.47) between CD on days 20 and 22 (area under the curve = 0.82 and 0.84, respectively). In conclusion, CD successfully detected most non-pregnant replacement heifers on day 20 and 22, while false negative results were absent (NPV = 100%).

Applied Use of Doppler Ultrasonography in Bovine Reproduction

“…Representative ultrasound images of luteal blood perfusion collected from cows classified as true positives, false positives, and true negatives are shown in Figures 1A-C. Luteal blood perfusion on days 20 and 22 after TAI were not different in cows or heifers classified as true-positive or false-positive (Holton et al, 2022a;Holton et al, 2022b;Figure 1D). Several factors could be driving the presence of false-positive diagnoses (active luteal blood perfusion in non-pregnant cows) observed when color Doppler ultrasonography is utilized around day 20 of gestation, including delayed ovulation during the estrus synchronization protocol, an intrinsic prolonged luteal phase, or a prolonged luteal phase due to pregnancy loss after conceptus secretion of interferon-t (Bazer et al, 2008).…”

“…Due to differences in CL morphometry (Sartori and Barros, 2011;Sartori et al, 2016) and early embryonic mortality (Reese et al, 2020) between subspecies, it was unclear if the accuracy of color Doppler examinations in Bos taurus and Bos indicus beef cattle populations were comparable. Therefore, Holton and colleagues recently evaluated the use of color Doppler in Bos taurus beef cows and replacement heifers (Holton et al, 2022a;Holton et al, 2022b; Table 1) using similar criteria to Pugliesi et al (2014) in Bos indicus females. Overall accuracies of color Doppler in postpartum cows were 86 and 91% on days 20 and 22 of gestation, respectively.…”