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.
Early pregnancy detection allows cattle producers to increase reproductive efficiency. Pregnancy failures associated with embryonic mortality represents an economic burden to the beef production industry. The present study evaluated the use of color doppler (CD) ultrasonography of specific ovarian structures and pregnancy-associated glycoproteins (PAG) in plasma as potential alternatives to diagnose pregnancy earlier than industry-standard methods in beef cows with Bos taurus genetics. Additionally, the present study evaluated the use of these methods to predict embryonic mortality during early gestation. The results of the present study indicate that: 1) CD can accurately recognize most nonpregnant cows with B. taurus genetics as early as 20 days after breeding. 2) Plasma concentrations of PAG resulted in suboptimal accuracy on day 25 of gestation. 3) Cows that undergo pregnancy loss between 29 and 100 d after breeding have decreased concentrations of PAG in their circulation on day 29, even though they were identify as pregnant with ultrasonography on the same day. 4) Both blood concentrations of PAG and luteal blood perfusion estimated by CD failed to accurately predict pregnancy loss.
Early pregnancy detection allows cattle producers to increase reproductive efficiency. Pregnancy failures associated with embryonic mortality represents an economic burden to the beef production industry. The present study evaluated the use of color doppler (CD) ultrasonography of specific ovarian structures and pregnancy-associated glycoproteins (PAG) in plasma as potential alternatives to diagnose pregnancy earlier than industry-standard methods in beef cows with Bos taurus genetics. Additionally, the present study evaluated the use of these methods to predict embryonic mortality during early gestation. The results of the present study indicate that: 1) CD can accurately recognize most nonpregnant cows with B. taurus genetics as early as 20 days after breeding. 2) Plasma concentrations of PAG resulted in suboptimal accuracy on day 25 of gestation. 3) Cows that undergo pregnancy loss between 29 and 100 d after breeding have decreased concentrations of PAG in their circulation on day 29, even though they were identify as pregnant with ultrasonography on the same day. 4) Both blood concentrations of PAG and luteal blood perfusion estimated by CD failed to accurately predict pregnancy loss.
摘要：
这项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）的血浆浓度在Bostaurus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）暴露于发情同步，然后进行固定时间的人工授精（第0天）。在第20天和第22天，进行B模式和CD超声检查以评估黄体（CL）形态和血液灌注。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天之间经历妊娠损失的母牛被分类为LEM。在第20天和第22天，与未怀孕的母牛相比，怀孕的母牛具有更大的血管化CL（所有响应变量P<0.001）。在第20天和第22天，CD的准确度分别为87％和92％，分别。PAG在第25天和第29天的准确度分别为84%和99%，分别。在第20天和第22天均未观察到CD的假阴性（FN）结果；但是，在第25天，PAG的FN结果为7.1％。与维持妊娠的奶牛相比，经历LEM的奶牛在妊娠第29天的循环PAG减少（P=0.04）；然而，LEM母牛和维持妊娠的母牛在第20天和第22天的黄体血液灌注(P≥0.53)或第25天的循环PAG(P=0.46)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%，分别。总之,在妊娠的第20天和第22天，CD可对金牛肉牛进行准确的妊娠诊断，没有FN结果。在经历LEM的奶牛中，PAG的循环浓度降低；然而，需要进一步的研究来利用PAG作为商业LEM的预测因子。
早期妊娠检测允许牛生产者提高繁殖效率。与胚胎死亡率相关的妊娠失败是牛肉生产行业的经济负担。本研究评估了血浆中特定卵巢结构和妊娠相关糖蛋白（PAG）的彩色多普勒（CD）超声检查作为具有Bostaurus遗传学的肉牛比行业标准方法更早诊断妊娠的潜在替代方法。此外,本研究评估了这些方法在预测妊娠早期胚胎死亡率方面的应用.本研究结果表明：1）CD可以在繁殖后20天准确识别大多数具有金牛芽孢杆菌遗传的未怀孕母牛。2)在妊娠第25天,PAG的血浆浓度导致准确度欠佳。3）繁殖后29至100天发生妊娠损失的母牛在第29天循环中的PAG浓度降低，即使在同一天通过超声检查确定了它们的妊娠。4）通过CD估计的PAG的血液浓度和黄体血液灌注均未能准确预测妊娠损失。
早期妊娠检测允许牛生产者提高繁殖效率。与胚胎死亡率相关的妊娠失败是牛肉生产行业的经济负担。本研究评估了血浆中特定卵巢结构和妊娠相关糖蛋白（PAG）的彩色多普勒（CD）超声检查作为具有Bostaurus遗传学的肉牛比行业标准方法更早诊断妊娠的潜在替代方法。此外,本研究评估了这些方法在预测妊娠早期胚胎死亡率方面的应用.本研究结果表明：1）CD可以在繁殖后20天准确识别大多数具有金牛芽孢杆菌遗传的未怀孕母牛。2)在妊娠第25天,PAG的血浆浓度导致准确度欠佳。3）繁殖后29至100天发生妊娠损失的母牛在第29天循环中的PAG浓度降低，即使在同一天通过超声检查确定了它们的妊娠。4）通过CD估计的PAG的血液浓度和黄体血液灌注均未能准确预测妊娠损失。
