Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS.
J Anim Sci. 2018 Feb 15;96(1):258-272. doi: 10.1093/jas/skx033.
Two experiments were conducted to determine relationships of blood metabolite concentrations, BW, BCS, and rump fat depth with postpartum ovulation and pregnancy risks, as well as their utility in predicting those outcomes in suckled beef cows. In experiment 1, plasma glucose collected 10 and 3 d before AI of suckled beef cows at seven locations did not differ between cows that had resumed estrous cycles (ovulated) before AI compared with anovulatory cows, whereas plasma glucose 3 d before AI was greater (P < 0.01) in cows that became pregnant compared with nonpregnant cows. Serum beta-hydroxybutyrate (BHB) tended (P = 0.09) to be less in ovulatory cows compared with anovulatory cows 10 d before AI, but was unrelated to pregnancy status. Receiver-operator derived true-positive (sensitivity) and false-positive (1-specificity) risks were determined for plasma glucose and serum BHB as predictors for postpartum ovulation and pregnancy status. Serum BHB 3 d before AI produced true-positive and false-positive risks of 82% and 37%, respectively, when predicting ovulatory status before AI. Serum BHB 10 d before AI produced a true-positive and false-positive risks of 92% and 25%, respectively, when predicting pregnancy status. In experiment 2, blood was collected weekly for 12 wk from multiparous suckled beef cows to assess blood metabolite concentrations in addition to concurrent weekly assessments of BW, BCS, and rump fat. When blood metabolites and physical measures were normalized to parturition reflecting changes occurring during the first 6 wk after calving, we observed reduced (P < 0.05) concentrations of serum BHB and NEFA, and greater (P < 0.05) rump fat and BCS in cows that ovulated before first AI, whereas reduced (P < 0.05) plasma glucose was characteristic of cows that became pregnant. When blood metabolites and physical measures were normalized to the onset of the AI program reflecting changes during 6 wk before AI, ovulatory cows had increased (P < 0.05) BCS and lower (P < 0.05) NEFA from 3 to 6 wk before the onset of the AI program compared with anovulatory cows. With all predictor variables in regression models, some multiple correlation coefficients (R2) exceeded 50% when predicting postpartum ovulatory status, but those for predicting pregnancy risk were less than 25%. Although measures of BCS and BHB during 6 wk after calving were related to postpartum ovulation risk, rump fat, glucose, BCS, and NEFA were associated with cows that were ovulatory and pregnant.
进行了两项实验，以确定血液代谢物浓度、BW、BCS 和臀部脂肪深度与产后排卵和妊娠风险的关系，以及它们在预测哺乳期肉牛这些结果中的效用。在实验 1 中，在七个地点收集的接受 AI 的哺乳期肉牛的血浆葡萄糖在发情周期恢复（排卵）的牛与不排卵的牛之间没有差异，而在 AI 前 3 天的血浆葡萄糖则更高（P<0.01）与未怀孕的牛相比，怀孕的牛。发情周期恢复的牛在 AI 前 10 天的血清β-羟丁酸（BHB）水平趋于（P=0.09）低于不排卵的牛，但与妊娠状态无关。使用接收者操作特性曲线（ROC）确定了血浆葡萄糖和血清 BHB 作为产后排卵和妊娠状态预测因子的真阳性（敏感性）和假阳性（1 特异性）风险。在预测 AI 前的排卵状态时，血清 BHB 在 AI 前 3 天产生的真阳性和假阳性风险分别为 82%和 37%。血清 BHB 在 AI 前 10 天产生的真阳性和假阳性风险分别为 92%和 25%，用于预测妊娠状态。在实验 2 中，每周从多胎哺乳期肉牛中采集血液 12 周，以评估血液代谢物浓度，同时对 BW、BCS 和臀部脂肪进行每周评估。当将血液代谢物和物理测量值与分娩相归一化，反映产后 6 周内发生的变化时，我们观察到发情周期恢复的牛的血清 BHB 和 NEFA 浓度降低（P<0.05），臀部脂肪和 BCS 增加（P<0.05），而首次 AI 前怀孕的牛的血浆葡萄糖降低（P<0.05）。当将血液代谢物和物理测量值与 AI 计划的开始相归一化，反映 AI 前 6 周内的变化时，与不排卵的牛相比，发情周期恢复的牛在 AI 计划开始前 3 至 6 周时的 BCS 增加（P<0.05），NEFA 降低（P<0.05）。在回归模型中使用所有预测变量时，预测产后排卵状态的一些多重相关系数（R2）超过 50%，但预测妊娠风险的系数则小于 25%。虽然产后 6 周内 BCS 和 BHB 的测量值与产后排卵风险有关，但臀部脂肪、葡萄糖、BCS 和 NEFA 与排卵和怀孕的牛有关。
