125 Anti-Müllerian Hormone (AMH): a biomarker for the ovarian reserve, ovarian function and fertility in dairy cows.

Abstract

This presentation 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 dairy cattle show: 1) Antral follicle count (AFC) during follicular waves is highly variable between individuals but very highly repeatable within individuals. 2) Cycling heifers with low (≤ 15 follicles ≥3 mm, ~20% of a herd) vs a high (≥25 AFC, ~20% of a herd) have: i) a smaller ovarian reserve; ii) higher FSH but lower AMH, androstenedione, estradiol and progesterone concentrations and a thinner endometrium; iii) decreased response of granulosal, thecal or luteal cells to FSH or LH; and iv) a poorer response to superovulation. 3) Cows with a very high AFC as heifers have reduced fertility, fewer lactations and shorter herd longevity. 4) Cows with a low vs intermediate AFC have reduced fertility, fewer lactations and shorter herd longevity. 5) AMH concentrations are static within individuals but highly positively correlated with AFC. 6) A single AMH measurement is highly positive correlated with the average of multiple AMH measurements on different days of the cycle and AFC. 7) Fertility is not correlated with circulating AMH concentration in heifers. 8) Dairy cows with low vs a higher AMH as heifers have reduced fertility and a shorter herd longevity. 9) AMH concentrations in dairy heifers is 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. Research support: NRI Grants no. 2004-35203-14781 and 2007-35203-18178; AFRI Grants 2013-67015-20962; MSU’s AgBioResearch; and Green Meadow Farms, Inc.