School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Republic of Ireland.
UCD Lyons Farm, Co. Kildare, Republic of Ireland.
Reprod Domest Anim. 2024 Jan;59(1):e14498. doi: 10.1111/rda.14498. Epub 2023 Oct 30.
Anti-Müllerian hormone (AMH) is secreted by granulosa cells of healthy, growing follicles and is positively correlated with the ovarian reserve. Maternal and environmental factors, such as nutrition, disease, parity and endocrine disruptors, are thought to have a profound impact on ovarian reserve development during early foetal life. For genetic progress, it can be advantageous to breed dairy replacements from heifers to expedite the generation interval; however, there is some evidence that nulliparous animals produce female offspring with smaller ovarian reserves compared with multiparous animals. The objective of this prospective, observational study was to determine whether maternal growth in the pre-conception and early gestational period of nulliparous dairy heifers is associated with pre-weaning AMH concentrations in their female offspring. Our hypothesis was that excessive growth in this period would negatively impact AMH concentrations. Seasonal, pasture-based dairy heifer calves (n = 156) born from nulliparous dams, from six Irish farms, were blood sampled at an average of 60 days of age in spring 2022 and tested for AMH. Mixed-effects linear regression models were constructed with Box-Cox transformed AMH concentration as the dependent variable. The independent variables tested included maternal average daily gain (ADG) from pre-breeding examination (PBE) to pregnancy diagnosis (PD) between 30 and 60 days in calf (DIC), ADG from PBE to PD over 60 DIC and ADG between the two PDs. Calf breed and age at sampling were forced into the models, and the farm was treated as a random effect in all models. We found that as ADG increased from the pre-breeding period to their first PD visit, the AMH concentration in their offspring reduced. However, ADG explained only a small amount of the variation in AMH concentrations (marginal R = 0.041). In conclusion, the results of our study suggest that excessive growth prior to conception and in early gestation of nulliparous heifers could impact the ovarian reserve of their female offspring, and may imply that farmers should avoid excessive growth in the immediate pre-breeding and early gestational periods.
抗苗勒管激素（AMH）由健康生长的卵泡的颗粒细胞分泌，与卵巢储备呈正相关。人们认为，母体和环境因素，如营养、疾病、产次和内分泌干扰物，对胎儿早期的卵巢储备发育有深远的影响。对于遗传进展来说，从小母牛中繁殖奶牛替代品以加速世代间隔是有利的；然而，有一些证据表明，与多产动物相比，初产动物所产的雌性后代的卵巢储备较小。本前瞻性观察研究的目的是确定小母牛在初情期和早期妊娠期的母体生长是否与雌性后代的断奶前 AMH 浓度有关。我们的假设是，该时期的过度生长会对 AMH 浓度产生负面影响。2022 年春季，来自六个爱尔兰农场的初产小母牛（n=156）在平均 60 日龄时进行血液采样，并检测 AMH。使用 Box-Cox 转换后的 AMH 浓度作为因变量构建混合效应线性回归模型。所测试的自变量包括小牛（DIC）从配种前检查（PBE）到妊娠诊断（PD）的 30-60 天内的母体平均日增重（ADG）、60 天以上的 PBE 至 PD 的 ADG 和两次 PD 之间的 ADG。小牛品种和采样时的年龄被强制纳入模型，所有模型中农场被视为随机效应。我们发现，随着从配种前时期到第一次 PD 就诊期间的 ADG 增加，其后代的 AMH 浓度降低。然而，ADG 仅能解释 AMH 浓度变化的一小部分（边缘 R2=0.041）。总之，本研究结果表明，初产小母牛在配种前和早期妊娠期间的过度生长可能会影响其雌性后代的卵巢储备，这可能意味着农民应避免在配种前和早期妊娠期间出现过度生长。
