Browsing by Author "Sarmiento Quito, Santiago Xavier"

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Control of the emergence of the follicular wave by the application of oestradiol benzoate, GnRH and follicular ablation in the late metaoestrous in heifers in the high tropics
(2020) Ayala Guanga, Luis Eduardo; Nieto Escandón, Pedro Emilio; Rodas Carpio, Ermes Ramiro; Sarmiento Quito, Santiago Xavier; Dután Sanango, Jorge Bolívar
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 were determined retrospectively when assessing the daily ultrasound. The application of BE (T1) caused an initial growth of the DF, then it was maintained and finally went to atresia, the peak of FSH appeared at 48h (0.87±0.21 ng/ml) and the onset of the follicular wave was at 3.2±0.15 d post-treatment. In T2, 55.5% of the heifers ovulated in 24h and 44.5% between 24-48h, the peak of FSH was at 24h post-treatment and the onset of the wave in 2.4±0.18 d. The T3 heifers showed the FSH peak at 24h and wave restarted at 1.8±0.15 days. It is concluded that the application of BE in the heifers of the study favoured then an earlier restart of the follicular wave. Besides, the presence of corpus luteum and DF prior to the application of GnRH and ablation allows a more solid and homogeneous restart of the follicular wave.
Valoración de ovocitos obtenidos mediante Ovum pick-up en vaquillas sometidas a protocolos alternativos de sincronización de la onda folicular y estimuladas con FSH-LH
(2019) Sarmiento Quito, Santiago Xavier; Naulaguari Tintín, Luis Miguel; Ayala Guanga, Luis Eduardo
The objective of the present study was to evaluate the quantity and quality of oocytes retrieved by Ovum pick-up (OPU) of native Holstein heifers, synchronized by three alternative protocols for restarting the follicular wave, followed by ovarian stimulation with (FSH-LH). The experimental units (n=9) were divided into three groups and interspersed in three treatments (T1= follicular ablation, T2= GnRH, T3= estradiol benzoate). A standard synchronization protocol was used prior to each repetition to homogenize its estrous cycle (day 0: progesterone implant 0.5g + 2mg BE, day 7: 0.5mg prostaglandin F2α + estrus detection patch + implant removal, day 8: 1mg BE). On the day of restarting the follicular wave in each treatment, 500 IU of FSH-LH were applied intramuscularly. 48 hours later, the OPU was performed. (Three sessions were conducted during the study at intervals between sessions of 21 days). The data were processed in the statistical program SPSS version 24, by means of the ANOVA test for the quantitative variables and Chi square to relate percentages. No statistical differences were found in the mean number of follicles visualized (11.7, 9.8, 9.0, respectively, P> 0.05) or in the percentage of recovered oocytes (52.4%, 55.7%, 61.7%, respectively, P> 0.05) or in the averages of the cumulus oocyte complexes (COC) (47.3%, 57.1%, 52.0%, respectively, P> 0.05). In conclusion, ovarian stimulation with FSH-LH at the time of the restart of the follicular wave, reached a similar average in the number of follicles visualized, as well as in the percentages of recovery of COC, for the production of embryos in vitro, regardless of the method used to restart the follicular wave