Department of Veterinary Medicine, University of Sassari, Sassari, Italy.
Molecular Reproductive Endocrinology Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI.
J Anim Sci. 2019 Apr 3;97(4):1446-1455. doi: 10.1093/jas/skz022.
This review summarizes studies we conducted to test the hypothesis that size of the ovarian reserve (number of healthy follicles and oocytes in ovaries) positively impacts ovarian function and fertility in cattle. Key results, primarily in Bos taurus dairy cattle, show that antral follicle count (AFC) during follicular waves is highly variable between individuals, but very highly repeatable within individuals. Cycling heifers with low (≤15 follicles ≥3 mm, ~20% of a herd) vs. a high AFC (≥25, ~20% of a herd) have a smaller ovarian reserve, higher FSH but lower anti-Müllerian hormone (AMH), androstenedione, estradiol, and progesterone concentrations. Moreover, cattle with low AFC have a thinner endometrium, decreased response of granulosal, thecal, or luteal cells to FSH or LH and a poorer response to superovulation compared to cattle with high AFC. Interestingly, cows with a very high AFC as heifers have reduced fertility, fewer lactations, and shorter herd longevity, whereas cows with a low vs. intermediate AFC have reduced fertility, fewer lactations, and shorter herd longevity. Anti-Müllerian hormone concentrations are static within individuals but highly positively correlated with AFC, but fertility is not correlated with circulating AMH concentration in heifers and dairy cows with low vs. a higher AMH as heifers have reduced fertility and a shorter herd longevity. Anti-Müllerian hormone concentrations in dairy heifers are a moderately heritable trait (36%), and negatively impacted by inadequate maternal nutrition during early pregnancy or high maternal somatic cell count. We conclude that genetic or environmental manipulations of AMH could enhance size of the ovarian reserve and ovarian function, thereby improving fertility, response to superovulation, and longevity in dairy cows.
这篇综述总结了我们进行的研究，以检验卵巢储备（卵巢中健康卵泡和卵母细胞的数量）大小是否对牛的卵巢功能和生育能力有积极影响的假设。主要在荷斯坦奶牛中的关键结果表明，在卵泡波期间，窦卵泡计数（AFC）在个体之间差异很大，但在个体内部非常高度可重复。与高 AFC（≥25，约占牛群的 20%）相比，低 AFC（≤15 个卵泡≥3mm，约占牛群的 20%）的循环小母牛具有更小的卵巢储备、更高的 FSH 但更低的抗苗勒管激素（AMH）、雄烯二酮、雌二醇和孕酮浓度。此外，AFC 较低的牛具有较薄的子宫内膜，颗粒细胞、膜细胞或黄体细胞对 FSH 或 LH 的反应性降低，并且对超数排卵的反应性较差。有趣的是，作为小母牛时 AFC 非常高的牛的繁殖力降低，泌乳期数减少，牛群寿命缩短，而 AFC 较低或中等的牛的繁殖力降低，泌乳期数减少，牛群寿命缩短。在个体内部，AMH 浓度是静态的，但与 AFC 高度正相关，但在低 AMH 的小母牛和奶牛中，生育力与循环 AMH 浓度无关，而作为小母牛时 AMH 较低的牛的生育力降低和牛群寿命缩短。奶牛小母牛的 AMH 浓度是一种中度可遗传性状（36%），并且受到妊娠早期母体营养不足或高母体体细胞计数的负面影响。我们得出结论，AMH 的遗传或环境操作可以增强卵巢储备和卵巢功能，从而提高奶牛的生育力、对超数排卵的反应性和牛群寿命。
