The success of superovulation protocols has been greatly limited by the number of embryos recovered for transfer into recipients. Improved protocols have been successful at stimulating a large number of follicles, but struggle in translating this into high numbers of ovulations and thus, embryos. The primary objective of this thesis was to increase ovulation rates in Holstein heifers following superovulation and to characterize the effect of varying pharmaceutical strategies on daily follicle development and numbers of ovulations. Experiment 1 demonstrated that half-doses of FSH did not significantly change the number of ovulations when compared to full doses. Data also indicated that we were able to induce a new cohort of stimulated follicles despite the presence of a dominant follicle (DF). Experiment 2 showed no significant effects of dose timing (once or twice daily) or quality (decreasing vs. non-decreasing) on the number of ovulations. We then investigated the effect of progesterone (P4) manipulation during superstimulation in Experiment 3. Results indicated that a moderate progesterone environment allows for the highest number of ovulations compared to short or long progesterone application groups. Lastly, we re-evaluated half-doses versus full doses of FSH with our newly developed protocol in Experiment 4. Again, there was no difference in ovulation numbers between the groups, indicating that half-doses of FSH are sufficient to induce reliable numbers of ovulations.
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