The response of the dominant follicle (DF), the profile of the FSH and estradiol and the onset of the follicular wave after the application of estradiol benzoate, GnRH, or follicular ablation in late metestrus were characterized in crossbred Holstein heifers, reared at 2500 meters above sea level and fed to grazing. Nine animals weighing 427.7±23.0 kg, body condition 2.7±0.1, age 26.7±1.4 months were used. Before the experiment, the heifers were synchronized and day 6 of the oestrous cycle was considered day zero (start of the experiment). There were three treatments: T1 = Oestradiol benzoate - BE (n=9), T2 = GnRH (n=9), T3 = Ablation (n=9). The evaluation of the DF was carried out by ultrasound every 24 hours, for 5 consecutive days. FSH and oestradiol levels were analysed every 5 days from day 0 by radioimmunoassay. The onset of the follicular wave and number of follicles recruited ...

The response of the dominant follicle (DF), the profile of the FSH and estradiol and the onset of the follicular wave after the application of estradiol benzoate, GnRH, or follicular ablation in late metestrus were characterized in crossbred Holstein heifers, reared at 2500 meters above sea level and fed to grazing. Nine animals weighing 427.7±23.0 kg, body condition 2.7±0.1, age 26.7±1.4 months were used. Before the experiment, the heifers were synchronized and day 6 of the oestrous cycle was considered day zero (start of the experiment). There were three treatments: T1 = Oestradiol benzoate - BE (n=9), T2 = GnRH (n=9), T3 = Ablation (n=9). The evaluation of the DF was carried out by ultrasound every 24 hours, for 5 consecutive days. FSH and oestradiol levels were analysed every 5 days from day 0 by radioimmunoassay. The onset of the follicular wave and number of follicles recruited ...