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.

中文翻译：

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黄体彩色多普勒超声和妊娠相关糖蛋白作为早期妊娠诊断工具和 Bos taurus 产后肉牛流产的预测因子

本研究的目的是评估黄体彩色多普勒 (CD) 超声检查和妊娠相关糖蛋白 (PAG) 血浆浓度在 Bos taurus 肉牛早期妊娠诊断中的应用。此外，CD 和 PAG 被评估为晚期胚胎/早期胎儿死亡率 (LEM) 的潜在预测因子。产后肉牛 (n = 212) 暴露于同步发情期，然后进行固定时间人工授精（第 0 天）。在第 20 天和第 22 天，进行 B 型和 CD 超声检查以评估黄体 (CL) 形态测量和血液灌注。此外，在第 25 天和第 29 天收集血液样本以量化 PAG 的循环浓度。第 29 天和第 100 天的常规超声检查被用作妊娠诊断的金标准方法。在第 29 天和第 100 天之间经历流产的奶牛被归类为 LEM。在第 20 天和第 22 天，与未怀孕的奶牛相比，怀孕奶牛的 CL 更大且血管化更多（所有响应变量 P < 0.001）。第 20 天和第 22 天的 CD 准确度分别为 87% 和 92%。PAG 在第 25 天和第 29 天的准确度分别为 84% 和 99%。在第 20 天和第 22 天均未观察到 CD 的假阴性 (FN) 结果；然而，第 25 天 PAG 的 FN 结果为 7.1%。与保持妊娠的奶牛相比，经历过 LEM 的奶牛在妊娠第 29 天减少了 (P = 0.04) 循环 PAG；然而，第 20 天和第 22 天的黄体血灌注（P ≥ 0.53）或第 25 天的循环 PAG（P = 0.46）在 LEM 奶牛和维持妊娠的奶牛之间没有差异。第 29 天 PAG 作为 LEM 预测因子的敏感性和特异性分别为 83% 和 77%。总之，CD 在妊娠第 20 天和第 22 天对 B. taurus 肉牛进行了准确的妊娠诊断，而没有 FN 结果。经历 LEM 的奶牛的 PAG 循环浓度降低；然而，需要进一步研究以在商业上利用 PAG 作为 LEM 的预测因子。