The objectives of this study were to determine (1) factors associated with serum concentration of insulin-like growth factor-1 (IGF-1); (2) the relationship between serum IGF-1 concentration during the first week postpartum and ovarian cyclicity status by 35 d postpartum (DPP); (3) an optimum serum IGF-1 concentration threshold predictive of pregnancy to first artificial insemination (P/AI), including its diagnostic values; (4) the associations among categories of serum IGF-1 concentration and reproductive outcomes (P/AI and pregnancy risk up to 150 and 250 DPP); and (5) single nucleotide polymorphisms (SNP) associated with phenotypic variation in serum IGF-1 concentration in dairy cows. Serum IGF-1 concentration was determined at 7 (±2.4; ±standard error of the mean) DPP in 647 lactating Holstein cows (213 primiparous, 434 multiparous) from 7 herds in Alberta, Canada. The overall mean, median, minimum, and maximum serum IGF-1 concentrations during the first week postpartum were 37.8 (±1.23), 31.0, 20.0, and 225.0 ng/mL, respectively. Herd, age, parity, precalving body condition score, and season of blood sampling were all identified as factors associated with serum IGF-1 concentrations. Although serum IGF-1 concentration during the first week postpartum had no association with ovarian cyclicity status by 35 DPP in primiparous cows, it was greater in cyclic than in acyclic multiparous cows (32.2 vs. 27.4 ng/mL, respectively). The optimum serum IGF-1 thresholds predictive of P/AI were 85.0 ng/mL (sensitivity = 31.9%; specificity = 89.1%) and 31.0 ng/mL (sensitivity = 45.5%; specificity = 66.9%) for primiparous and multiparous cows, respectively. When cows were grouped into either high or low IGF-1 categories (greater or less than or equal to 85.0 ng/mL for primiparous cows and greater or less than or equal to 31.0 ng/mL for multiparous cows, respectively), primiparous cows with high IGF-1 had 4.43 times greater odds of P/AI and a tendency for higher pregnancy risk up to 150 DPP than those with low IGF-1, but not up to 250 DPP. Likewise, multiparous cows with high IGF-1 had 1.61 times greater odds of P/AI than those with low IGF-1. Pregnancy risk up to 150 and 250 DPP, however, did not differ between IGF-1 categories in multiparous cows. Moreover, 37 SNP across 10 Bos taurus autosomes were associated with variation in serum IGF-1 concentration, and 4 previously identified candidate genes related to fertility that were in linkage disequilibrium with some of these SNP were also identified.

这项研究的目的是确定（1）与胰岛素样生长因子-1 （IGF-1）的血清浓度有关的因素；（2）产后35 d（DPP）产后第一周血清IGF-1浓度与卵巢循环状态之间的关系；（3）最佳血清IGF-1浓度阈值可预测首次人工授精的妊娠（P / AI），包括其诊断值；（4）血清IGF-1浓度类别与生殖结局之间的关联（P / AI和最高150和250 DPP的妊娠风险）；（5）与奶牛血清IGF-1浓度表型变异有关的单核苷酸多态性（SNP）。在加拿大艾伯塔省的7个牛群中，对647头泌乳的荷斯坦奶牛（213头生，434头）的血清DGF测定为7（±2.4；平均值的标准误差）。产后第一周的血清IGF-1总平均浓度，中位数，最低和最高浓度分别为37.8（±1.23），31.0、20.0和225.0 ng / mL。牛群，年龄，胎次，分娩前的身体状况评分和采血季节均被确定为与血清IGF-1浓度相关的因素。尽管产后第一周血清IGF-1的浓度与35 DPP的卵巢周期性状态无关，但在周期性牛中比在无环多胎牛中更高（分别为32.2和27.4 ng / mL）。对于初乳和多胎母牛，预测P / AI的最佳血清IGF-1阈值分别为85.0 ng / mL（敏感性= 31.9％；特异性= 89.1％）和31.0 ng / mL（敏感性= 45.5％；特异性= 66.9％），分别。当将母牛分为高或低IGF-1类别时（初产母牛分别大于或等于85.0 ng / mL，多产母牛大于或小于或等于31.0 ng / mL），初产母牛具有高IGF-1的P / AI机率高4.43倍，并且高达150 DPP的妊娠风险比低IGF-1的高，但最高不超过250 DPP。同样，IGF-1高的多头母牛的P / AI几率是IGF-1低的多头母牛的1.61倍。然而，在多胎牛中，IGF-1类别之间高达150和250 DPP的妊娠风险没有差异。此外，跨10个站点的37个SNP金牛座常染色体与血清IGF-1浓度的变化有关，并且还鉴定了4个先前鉴定的与生育力相关的候选基因，这些基因与其中一些SNP连锁不平衡。