87 OVARIAN RESERVE, EMBRYO PRODUCTION, AND THEIR CORRELATION WITH ANTI-MÜLLERIAN HORMONE (AMH) IN HOLSTEIN COWS

Abstract

Anti-Müllerian hormone (AMH) is a small peptide hormone that has been associated with ovarian follicular reserve in humans and in some animal species including bovine. Profiles of AMH, as well as the relationship between serum AMH to oocyte number and in vivo embryo production, were evaluated in Holstein cows. AMH levels were determined in 15 unstimulated cows at monthly intervals for 4 months and in 394 male and 399 female developing Holstein animals from birth to adulthood. Also, AMH was measured in 41 heifers at the time of ovum pick-up (OPU) and 125 heifers at the time of embryo flushing. Superovulation was induced before OPU or embryo flushing using a modified Ovsynch protocol with 4 days of decreasing FSH (Pluset H®, MOFA Global, Verona, WI, USA). Blood samples were collected using serum tubes and spun within 2 h. The samples were stored at –20°C until evaluated for AMH using the AMH-Bovine specific immunoassay® (MOFA Global). AMH levels in males and females peaked at 2 months of age and then decrease as they reached adulthood. The average AMH level of adult cows was stable for each of the 4 monthly measurements, with a high correlation between all values per animal (r² = 0.9077; P < 0.01), suggesting that AMH levels are consistent for at least 4 consecutive months. However, AMH levels were lowest during the summer months, suggesting a seasonal change in AMH secretion. Animals repeatedly ovarian stimulated showed decreasing AMH levels (509 ± 295, 299 ± 210, 211 ± 119) with subsequent stimulations. There was also a significant decrease in the number of embryos recovered (5.7 ± 4, 2.2 ± 1.9; P = 0.02); however, the number of oocytes was not altered by multiple stimulations (9.9 ± 9.8, 8.1 ± 6.2; P = 0.57). Because AMH and embryo numbers decreased after multiple stimulations, the first AMH value and results of the first OPU or embryo flush were used for the correlation of AMH to the number of oocytes or embryos. Animals were separated into 3 AMH categories: low (<100), normal (100–400), and high (>400 pg mL^–1). High AMH OPU animals had significantly higher numbers of oocytes than the normal or low AMH groups (13.8 ± 9.2, 9.2 ± 5.3, 5.6 ± 3.9; P = 0.001). High AMH flushed animals had significantly higher numbers of embryos than animals with low AMH (10.9 ± 8.0, 5.7 ± 5; P = 0.002). Statistical analyses were performed using Statview 5. Differences were determined using Student's t-test; P < 0.05 was considered significant. In conclusion, AMH serum concentrations are consistent over multiple months; however, blood should not be taken for animal selection by AMH after ovarian stimulations have begun and should be interpreted with caution during the summer months. AMH is highly associated with superovulation response and oocyte and embryo production and should improve efficiency of multiple-ovulation embryo transfer.