Abstract #265

# 265
Evaluating anti-Müllerian hormone as a reproductive tool in dairy cows.
K. Alward*1, W. Graves1, R. Palomares2, A. Nelson1, J. Bohlen1, 1University of Georgia Animal and Dairy Science, Athens, GA, 2University of Georgia College of Veterinary Medicine, Athens, GA.

Anti-Müllerian hormone (AMH) is produced by granulosa cells, found in early antral follicles on the ovary. Higher circulating AMH concentrations are indicative of a larger number of viable follicles present and published data shows that cows with low AMH have lower pregnancy risk and greater incidence of pregnancy loss between d 30 and 65 of gestation. These and other studies indicate that AMH, used as a marker of fertility, may provide use in determining breeding strategies for dairy cattle. The objective of this study was to examine whether categorization of animals based on AMH levels (HIGH or LOW) can allow for tailored breeding programs to increase first service pregnancy risk. Lactating, Holstein cows (n = 197) were enrolled at 45–60 d in milk (DIM) at which time blood was collected and analyzed for AMH (Ansh Labs, Webster, TX) and transrectal ultrasonography was performed to record antral follicle count (AFC), presence of corpora lutea (CL) and any reproductive tract anomalies. Animals were then randomly assigned to either an estrous detection (ED; n = 60) or a timed artificial insemination (TAI; n = 137) breeding protocol and first service conception risk was recorded. Animals were further categorized as HIGH (>200 pg/mL; n = 109) or LOW (<200 pg/mL; n = 88) AMH based on the profile of AMH distribution. AMH concentration was positively correlated with AFC (P = 0.0002). First-service conception risk was not affected by breeding protocol, AMH category, DIM or lactation number (P > 0.05). However, milk weight at breeding may have an impact on AMH level (P = 0.0621). With a normal distribution of AMH levels in the current research group, tailored breeding programs based on AMH categorization may only prove beneficial when the extreme outliers in the HIGH/LOW classifications are targeted.

Key Words: anti-Müllerian hormone, breeding strategies, fertility