Abstract
This study evaluated Anti-Mullerian hormone (AMH) and/or follicle counts as predictors of subsequent superovulatory response and embryo production in 79 beef cows. Before superovulation, 3 to 5 mm follicles presented on the ovaries of donor cows were counted, and blood was collected for measure of serum AMH. Across cows, serum AMH ranged from 0.013 to 0.898 ng/mL, with a mean of 0.293 ng/mL. The distribution of both AMH concentrations and follicle counts were divided into quartiles (AMH Q1 through Q4, with Q1 the lowest and Q4 the highest) for analysis. 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 corpora lutea (CL) than cows in AMH Q1. The mean number of embryos recovered from donor cows in AMH Q4 was greater (P < 0.001) than those recovered from cows in either AMH Q1 or 2, but similar to that of AMH Q3. 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). 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 were recovered from cows with the highest follicle counts (F Q4) as compared with cows having lower (F Q1 and 2) follicle counts. Results confirm that relative AMH concentration was positively correlated with number of small antral follicles in the ovaries of cows; both AMH measure and antral follicle counts might be used to predict subsequent superovulatory response in beef cows.
Highlights
Since the development of cattle superovulation and non-surgical embryo recovery in the 1970s, the unpredictability and variability of the superovulatory response has remained a major obstacle
This study evaluated Anti-Mullerian hormone (AMH) and/or follicle counts as predictors of subsequent superovulatory response and embryo production in 79 beef cows
The mean number of embryos recovered from donor cows in AMH Q4 was greater (P < 0.001) than those recovered from cows in either AMH Q1 or 2, but similar to that of AMH Q3
Summary
Since the development of cattle superovulation and non-surgical embryo recovery in the 1970s, the unpredictability and variability of the superovulatory response has remained a major obstacle. The pool of small antral follicles available for stimulation should dictate the superovulatory response. Erickson [2] reported the pool of primordial follicles within the ovaries harvested from heifers under 1 year of age ranged from ~60,000 to 240,000. In comparing the pool of primordial follicles in ovaries harvested from 5 year old fertile versus infertile cows, Erickson [2] reported over a 6-fold difference (~119,000 versus 18,000, respectively). If the pool of antral follicles available for stimulation explains the variation in superovulation, quantification of antral follicles could be used to predict and possibly adjust superovulatory treatments for more consistent response
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