Important components of a successful embryo transfer program in cattle are the superovulatory response and embryo production. Anti-Müllerian hormone (AMH) and antral follicle count (AFC) have been proposed as biomarkers of the reproductive response in superovulated cattle; however, their predictive ability appears to be influenced by climate. Objective herein was to evaluate AMH and AFC as predictors of the number of ovarian follicles, corpora lutea, collected embryos and transferable embryos in cows managed in northwest Mexico under different climates. Multiparous Simmental beef donor cows were assigned in two experimental climatic groups, cool (January 15– May 14; n=66) and warm (May 15– September 14; n=62). All cows were given a superovulatory treatment, and then subjected to artificial insemination and non-surgical embryo collection. Transrectal ultrasonography was performed to determine AFC. Blood samples were collected to measure blood AMH concentrations. A mixed effects model was used to analyze superovulatory and embryo production responses in cattle including AMH, AFC and climate as fixed effects, age as covariate and herd as random effect. All fixed effects resulted as significant (P<0.05) sources of variation for the evaluated traits, and interactions between AMH/AFC with climate were observed but only for transferable embryos. Pearson correlations were calculated between AMH/AFC with superovulatory and embryo production variables for cool and warm experimental groups, and a regression analyses was performed to quantify these relationships. Cows with either AMH>400 pg/mL or intermediate to higher AFC increased (P<0.05) mean values for superovulatory and embryo production variables, suggesting both AMH and AFC as predictors. Climate also influenced cow responses as number of follicles, corpora lutea, as well as collected and transferable embryos increased 33, 38, 40 and 35%, respectively, during cool- (8-23 °C) compared to warm-climate (24-34 °C; P<0.05). Both AMH and AFC were moderately correlated with number of follicles, corpora lutea and collected embryos (P<0.05) and highly correlated with transferable embryos (P<0.01) during cool climate; conversely, these correlations were low (P>0.05) for donor cows managed in the warm months. Regression analyses suggested that total number of transferable embryos increased 0.005 per 1 pg/mL of AMH and improved 0.484 per 1 unit of AFC. In conclusion, superovulatory and embryo production responses in Simmental beef cows appear to be closely associated with AMH and AFC, which are proposed as predictors for transferable embryos; however, such relationships were only detectable in absence of heat stress.

牛成功胚胎移植计划的重要组成部分是超排卵反应和胚胎生产。抗苗勒管激素 (AMH) 和窦卵泡计数 (AFC) 已被提议作为超排卵牛生殖反应的生物标志物；然而，它们的预测能力似乎受到气候的影响。本文的目的是评估 AMH 和 AFC 作为在不同气候下墨西哥西北部管理的奶牛中卵巢卵泡、黄体、收集的胚胎和可移植胚胎数量的预测因子。经产的西门塔尔牛肉供体奶牛被分为两个实验气候组，凉爽（1 月 15 日至 5 月 14 日；n=66）和温暖（5 月 15 日至 9 月 14 日；n=62）。对所有奶牛进行超排卵处理，然后进行人工授精和非手术胚胎采集。进行经直肠超声检查以确定 AFC。收集血液样本以测量血液 AMH 浓度。混合效应模型用于分析牛的超排卵和胚胎生产反应，包括作为固定效应的 AMH、AFC 和气候，作为协变量的年龄和作为随机效应的牛群。所有固定效应的结果都显着（P <0.05）观察到评估性状的变异来源，以及AMH / AFC与气候之间的相互作用，但仅针对可移植胚胎。计算冷热实验组的 AMH/AFC 与超排卵和胚胎生产变量之间的 Pearson 相关性，并进行回归分析以量化这些关系。AMH>400 pg/mL 或中等至更高 AFC 的奶牛增加了 ( P <0.05) 超排卵和胚胎生产变量的平均值，表明 AMH 和 AFC 都是预测因子。气候也影响奶牛的反应，因为与温暖气候（24-23°C）相比，在凉爽（8-23°C）期间卵泡、黄体以及收集和可移植胚胎的数量分别增加了 33%、38%、40% 和 35%。 34℃；P<0.05）。在凉爽气候下，AMH和AFC均与卵泡数、黄体数和收集胚胎数呈中度相关（P <0.05），与可移植胚胎高度相关（P <0.01）；相反，对于在温暖月份管理的供体奶牛，这些相关性很低（P > 0.05）。回归分析表明，每 1 pg/mL AMH 可移植胚胎总数增加 0.005，每 1 单位 AFC 增加 0.484。总之，西门塔尔肉牛的超排卵和胚胎生产反应似乎与 AMH 和 AFC 密切相关，它们被提议作为可移植胚胎的预测指标；然而，只有在没有热应激的情况下才能检测到这种关系。