Andrade João Paulo N, Domingues Rafael R, Monteiro Pedro L J, Dias José Ricardo, Pimenta Cesar, Guimarães Afonso S, Barbosa Leuton, Merhi Sami, Sartori Roberto, Wiltbank Milo C
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Wisconsin, 53706, USA.
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Wisconsin, 53706, USA; Department of Animal Sciences, The Ohio State University, Columbus, OH, 43210, USA.
Theriogenology. 2024 Dec;230:15-20. doi: 10.1016/j.theriogenology.2024.08.014. Epub 2024 Aug 23.
The aim was to evaluate the efficiency of two different ultrasonographic systems, Doppler mode vs. Two-dimensional mode (B mode), to identify the pregnancy status of beef cows and heifers on day 21 (D21) after Timed Artificial Insemination (TAI). The experiment was performed on a commercial beef farm in central-west region of Brazil using 1895 Nelore heifers and cows. All females had ovulation synchronized for a TAI that was performed on D0. Twenty-one days after the TAI, all animals had their ovaries evaluated by ultrasound for pregnancy diagnosis based on the size of the corpus luteum (CL). Using B mode ultrasonography, females without a CL or with a CL ≤ 10 mm in diameter were considered nonpregnant, whereas females with a CL > 10 mm in diameter were considered potentially pregnant. After the B mode examination, the Doppler mode was turned on, and the CL was evaluated by the subjective percentage of blood perfusion in the total area of the CL. Using Doppler mode, females were considered nonpregnant if they had no CL or the CL had ≤25 % of the total area with detectable blood perfusion, whereas animals with >25 % blood perfusion in the CL were considered potentially pregnant. The results for each method (potentially pregnant or nonpregnant) were later compared with the gold standard technique, which was a pregnancy diagnosis on D33 after TAI using ultrasound with visualization of an embryonic heartbeat. The accuracy was determined using the 2 × 2 contingency table approach. The area under the curve using the receiver operating characteristic curve for Doppler mode and B mode were 0.929 and 0.902 (P < 0.01), respectively. There were almost no false negatives (designated non-pregnant but later pregnant at D33) with either technique (0.2 % vs. 0.3 %; P = 0.65 for Doppler mode vs. B mode, respectively). False positives (designated pregnant but non-pregnant on D33) were greater for B mode compared to Doppler (19.1 % vs. 14.0 %; P < 0.01). This resulted in Doppler mode having similar high values as B mode for Negative Predictive Value (99.9 vs. 99.6 %; P = 0.85) and Sensitivity (99.8 vs. 99.7 %; P = 0.86) but there were differences in Specificity (86 vs. 80.9 %; P < 0.01), Positive Predictive Value (88 vs. 84.3 %; P < 0.01), and Accuracy (93.0 vs. 90.4 %; P < 0.01). In conclusion, evaluation of CL blood perfusion by Doppler produced greater accuracy in the early identification of nonpregnant heifers and cows on D21 after TAI than measurement of CL diameter with B mode ultrasound; although both had over 90 % accuracy in identifying pregnant and nonpregnant females.
本研究旨在评估两种不同超声系统（多普勒模式与二维模式（B 模式））在定时人工授精（TAI）后第 21 天（D21）鉴定肉牛母牛和小母牛妊娠状态的效率。实验在巴西中西部地区的一个商业肉牛场进行，使用了 1895 头内洛尔小母牛和母牛。所有雌性动物的排卵均同步，于 D0 进行 TAI。TAI 后 21 天，所有动物通过超声检查卵巢，根据黄体（CL）大小进行妊娠诊断。使用 B 模式超声检查时，无 CL 或 CL 直径≤10 mm 的雌性被视为未妊娠，而 CL 直径>10 mm 的雌性被视为可能妊娠。B 模式检查后，开启多普勒模式，通过 CL 总面积中血流灌注的主观百分比评估 CL。使用多普勒模式时，如果没有 CL 或 CL 中可检测到血流灌注的总面积≤25%，则雌性被视为未妊娠，而 CL 中血流灌注>25%的动物被视为可能妊娠。随后将每种方法（可能妊娠或未妊娠）的结果与金标准技术进行比较，金标准技术是在 TAI 后第 33 天使用超声可视化胚胎心跳进行妊娠诊断。使用 2×2 列联表方法确定准确性。多普勒模式和 B 模式的受试者工作特征曲线下面积分别为 0.929 和 0.902（P<0.01）。两种技术几乎均无假阴性（被判定未妊娠但在 D33 时后来妊娠）（分别为 0.2%对 0.3%；多普勒模式与 B 模式相比，P = 0.65）。与多普勒模式相比，B 模式的假阳性（被判定妊娠但在 D33 时未妊娠）更多（19.1%对 14.0%；P<0.01）。这导致多普勒模式在阴性预测值（99.9%对 99.6%；P = 0.85）和敏感性（99.8%对 99.7%；P = 0.86）方面与 B 模式具有相似的高值，但在特异性（86%对 80.9%；P<0.01）、阳性预测值（88%对 84.3%；P<0.01）和准确性（93.0%对 90.4%；P<0.01）方面存在差异。总之，与使用 B 模式超声测量 CL 直径相比，通过多普勒评估 CL 血流灌注在 TAI 后第 21 天早期鉴定未妊娠小母牛和母牛方面具有更高的准确性；尽管两者在鉴定妊娠和未妊娠雌性方面的准确性均超过 90%。
