Pohler K G, Peres R F G, Green J A, Graff H, Martins T, Vasconcelos J L M, Smith M F
Division of Animal Sciences, University of Missouri, Columbia, Missouri, USA.
Aluno do Programa de Pós Graduação em Zootecnia da Faculdade de Medicina Veterinária e Zootecnia-UNESP, Botucatu, São Paulo, Brazil.
Theriogenology. 2016 Jun;85(9):1652-1659. doi: 10.1016/j.theriogenology.2016.01.026. Epub 2016 Feb 4.
The primary objective was to determine if circulating concentration of bovine pregnancy-associated glycoproteins (bPAGs) on Day 30 after artificial insemination (AI) may serve as a marker of late embryonic mortality in Bos indicus (Nelore) beef cows. In experiment 1, postpartum Nelore beef cows (n = 56) were artificially inseminated at a fixed time (Day 0) after synchronization of ovulation. Serum samples were collected on Days 0, 21, 24, 27, and 30 after AI. The first significant increase (P < 0.0001) in serum bPAGs after insemination occurred on Day 24 of gestation. In experiment 2, ovulation was synchronized in postpartum Nelore beef cows (n = 1460) and AI was received at a fixed time. Pregnancy diagnosis and blood sample collection were carried out on Days 28 to 30 after insemination. Cows that maintained a pregnancy from Days 28 to 100 of gestation (n = 714) had significantly (P < 0.0001) higher circulating concentrations of bPAGs on Day 28 compared with cows that did not maintain a pregnancy (embryonic mortality [EM]) until Day 100 (n = 89). When Day 28 bPAG concentration was included in a logistic regression model to predict pregnancy maintenance until Day 100 of gestation, there was an increase (P < 0.0001) in the probability of maintaining pregnancy as maternal concentrations of bPAGs increased. A receiver operating characteristic curve was generated to determine bPAG concentrations on Day 28 that should predict embryonic survival or mortality with an accuracy of 95% or more. On the basis of the positive and negative predicative value analysis, at Day 28 of gestation a circulating concentration of bPAGs greater than 7.9 ng/mL was 95% accurate in predicting embryonic maintenance (to Day 100); a concentration of bPAGs less than 0.72 ng/mL was 95% accurate in predicting EM by Day 100. In experiment 3, the preceding model was tested in a separate set of Nelore beef cows to validate whether bPAGs would serve as an accurate measure of late embryonic mortality. Ovulation was synchronized in 650 Nelore cows and received AI at a fixed time. Pregnancy diagnosis and bPAG sampling were performed at Day 28 of gestation. Only pregnant cows were included in the analysis. On the basis of the previously reported bPAG cutoff values, the test was 95% accurate in predicting late embryonic mortality at Day 28 of gestation. In summary, bPAGs seem to be a good marker for predicting EM between Days 28 and 100 of gestation and suggest that this model could help dissect the molecular mechanisms leading to late EM.
主要目的是确定人工授精（AI）后第30天牛妊娠相关糖蛋白（bPAGs）的循环浓度是否可作为印度瘤牛（内罗牛）肉牛晚期胚胎死亡的标志物。在实验1中，产后内罗牛肉牛（n = 56头）在排卵同步后的固定时间（第0天）进行人工授精。在人工授精后的第0、21、24、27和30天采集血清样本。授精后血清bPAGs的首次显著升高（P < 0.0001）发生在妊娠第24天。在实验2中，对产后内罗牛肉牛（n = 1460头）进行排卵同步，并在固定时间进行人工授精。在授精后的第28至30天进行妊娠诊断和血样采集。与在第100天前未维持妊娠（胚胎死亡[EM]）的母牛（n = 89头）相比，在妊娠第28至100天维持妊娠的母牛（n = 714头）的bPAGs循环浓度显著更高（P < 0.0001）。当将第28天的bPAG浓度纳入逻辑回归模型以预测妊娠维持至妊娠第100天时，随着母体bPAGs浓度的增加，维持妊娠的概率增加（P < 0.0001）。生成了一条受试者工作特征曲线，以确定第28天的bPAG浓度，该浓度应能以95%或更高的准确率预测胚胎存活或死亡。基于阳性和阴性预测值分析，在妊娠第28天，bPAGs循环浓度大于7.9 ng/mL时，预测胚胎维持（至第100天）的准确率为95%；bPAGs浓度小于0.72 ng/mL时，预测第100天前胚胎死亡的准确率为95%。在实验3中，在另一组内罗牛肉牛中测试了上述模型，以验证bPAGs是否可作为晚期胚胎死亡的准确指标。对650头内罗牛进行排卵同步，并在固定时间进行人工授精。在妊娠第28天进行妊娠诊断和bPAG采样。分析仅纳入怀孕母牛。根据先前报道的bPAG临界值，该测试在预测妊娠第28天的晚期胚胎死亡时准确率为95%。总之，bPAGs似乎是预测妊娠第28至100天胚胎死亡的良好标志物，表明该模型有助于剖析导致晚期胚胎死亡的分子机制。
