233 ANTI-MÜLLERIAN HORMONE AS A PREDICTIVE ENDOCRINE MARKER FOR SUPEROVULATORY RESPONSE AND EMBRYO PRODUCTION IN BEEF CATTLE

A study investigated the use of anti-Mullerian hormone (AMH) and/or follicle counts as a predictor of subsequent superovulatory response and embryo production in 79 beef cows. Before initiation of superovulation, ultrasonography was used to scan the ovaries of each donor cow to record the number of 3 to 5 mm follicles present, and a blood sample was collected for measure of serum AMH. At the time of embryo collection, the ovaries of donor cows were palpated to estimate the number of corpora lutea (CL) present on each ovary. Recovered embryos were evaluated for stage of development and morphological quality. Across cows, serum AMH ranged from 0.013 to 0.898 ng mL–1, with a mean of 0.293 ng mL–1. The distribution of AMH concentrations was divided into quartiles (AMH Q1 through Q4, with Q1 the lowest and Q4 the highest, ng mL–1) for analysis (ANOVA). Number of donors/collections in AMH Q1 through Q4 was 26, 22, 24, and 24, respectively. Donor cows in AMH Q4 had a greater (P < 0.001) number of 3- to 5-mm follicles at the start of superovulation than did donors in either Q1 or Q2. At embryo collection, cows in AMH Q3 and 4 had more (P < 0.001) palpable CL than cows in AMH Q1. The mean number of embryos recovered from donor cows in AMH Q4 (20.1 ± 1.8) was greater (P < 0.001) than those recovered from cows in either AMH Q1 (9.8 ± 1.8) or 2 (9.4 ± 1.9), but similar to that of AMH Q3 (15.5 ± 1.8). Percentages of recovered embryos classified as transferrable, degenerate, or unfertilized were similar (P ≥ 0.275) across AMH quartiles. Analysis indicated that AMH was positively correlated (P < 0.001) with mean follicles (r = 0.458), CL (r = 0.452), and embryos recovered (r = 0.430). To determine if follicle counts at the start of superovulation are predictive of superovulatory response, the distribution of follicle counts was divided into quartiles (F Q1 through Q4, with Q1 the lowest and Q4 the highest) for analysis. Donor cows with higher follicle counts (F Q3 and 4) at the start of superovulation had more (P < 0.001) palpable CL at embryo collection than donor cows in F Q1 or 2. More (P < 0.001) embryos (20.0 ± 2.2 v. 9.6 ± 1.8 and 11.6 ± 1.6) were recovered from cows with the highest follicle counts (F Q4) compared with cows having lower (F Q1 and 2) follicle counts, respectively. The percentage of transferable embryos and unfertilized ova were similar (P ≥ 0.688) across follicle count quartiles. As was noted for AMH, mean number of follicles at the start of superovulation was positively correlated (P < 0.001) with mean CL (r = 0.556) and mean embryos (r = 0.423) but not percentages of viable or degenerate embryos or unfertilized oocytes (P ≥ 0.153). Results confirm that relative AMH concentration was positively correlated with number of small antral follicles in the ovaries of cows and might be used to either predict superovulatory response or possibly adjust superovulatory regimen to improve superovulatory response. Further study is needed to determine the effectiveness of using either AMH concentration or follicle counts to adjust superovulatory regimens.