Research data on the Influence of GnRH at the beginning of the ovulation synchronization protocol on ovarian dynamics and haemodynamics in dairy cows

Data regarding the evaluation of ovarian dynamics and hemodynamics and serum progesterone levels in cows that, after undergoing pre-synchronization, received or did not receive GnRH at the beginning of the ovulation synchronization protocol for fixed-time artificial insemination. The objective of this study was to evaluate the effects of gonadotropin-releasing hormone (GnRH) administration at the beginning of a fixed-time artificial insemination (FTAI) protocol on ovarian dynamics and hemodynamics, assessed by Doppler ultrasonography, in Holstein cows. The research was developed under the hypothesis that GnRH induces ovulation, increasing the number of corpora lutea and consequently the serum progesterone level. In addition to confirming the hypothesis, we identified that Holstein cows with higher serum progesterone levels during follicular emergence and development have ovulatory follicles with greater blood supply.