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 ...

The aim of this study was to evaluate the effects of gonadotropin treatment and the interval between ovarian stimulation with FSH/LH and the follicular aspiration session, on the quantity and quality of the cumulus oocyte complexes (COCs) obtained by ovum pick up (OPU) ) in Ecuadorian Creole heifers. Four heifers were randomly assigned to four groups (FHS/LH 40h; FSH/LH 48h; control 40h; control 48h). In two groups a dose (0.011 mg, IM) of GnRH was applied on day 0, followed by 500 IU, IM, of FSH/LH on day 2, and the OPU session at 40 (FSH/LH 40 h) or 48 hours (FSH/LH 48h) after the application of gonadotropin. In the other two groups, FSH/LH was replaced by a physiological solution. There was no statistical difference in the recovery rate of COCs between FSH/LH 40h and FSH/LH 48h, but approximately twice as many COCs (p<0.05) were obtained than in those who did not receive ovarian st...

The aim of this study was to evaluate the effects of gonadotropin treatment and the interval between ovarian stimulation with FSH/LH and the follicular aspiration session, on the quantity and quality of the cumulus oocyte complexes (COCs) obtained by ovum pick up (OPU) ) in Ecuadorian Creole heifers. Four heifers were randomly assigned to four groups (FHS/LH 40h; FSH/LH 48h; control 40h; control 48h). In two groups a dose (0.011 mg, IM) of GnRH was applied on day 0, followed by 500 IU, IM, of FSH/LH on day 2, and the OPU session at 40 (FSH/LH 40 h) or 48 hours (FSH/LH 48h) after the application of gonadotropin. In the other two groups, FSH/LH was replaced by a physiological solution. There was no statistical difference in the recovery rate of COCs between FSH/LH 40h and FSH/LH 48h, but approximately twice as many COCs (p<0.05) were obtained than in those who did not receive ovarian st...