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 competence of oocytes according to follicle size to restart meiosis was evaluated. The follicles were measured and classified as Group 1 (G1 <4 mm), Group 2 (G2 4-8 mm) and Group 3 (G3 >8 mm). The aspiration was performed by group with a 21G needle connected to a vacuum pump, with a pressure of 65 mmHg. The complex oocyte clusters (COCs) recovered were classified as suitable and unsuitable to produce embryos in vitro, according to the characteristics of the cumulus and the cytoplasm. Eligible and unsuitable COCs were assessed with the Brilliant Cresyl Blue (BCB) and were classified into BCB+ and BCB-. In vitro maturation (IVM) was carried out in microdroplets, incubated in a 5% CO2 chamber, 38.5 °C and 90% humidity for 24 hours. The meiotic progression was determined by extrusion of the polar corpuscle by epifluorescence under an inverted microscope. Oocyte morphometry was est...

Se evaluó la capacidad de los ovocitos de folículos según su tamaño para reiniciar la meiosis. Los folículos se midieron y clasificaron como Grupo 1 (G1 <4 mm), Grupo 2 (G2 4-8 mm) y Grupo 3 (G3 >8 mm). La aspiración se realizó por grupo con una aguja 21G conectada a una bomba de vacío, con una presión de 65 mmHg. Los complejos cúmulos de ovocitos (COC) recuperados se clasificaron como adecuados y no adecuados para la producción de embriones in vitro, de acuerdo con las características del cúmulo y del citoplasma. Los COC elegibles e inadecuados se valoraron con la prueba de azul brillante de Cresilo (BCB) y se clasificaron en BCB+ y BCB-. La maduración in vitro (IVM) se llevó a cabo en microgotas, incubadas en una cámara de CO2 al 5%, 38.5 °C y 90% de humedad durante 24 horas. La progresión meiótica se determinó por extrusión del corpúsculo polar mediante epi...

The objective of the present study was to evaluate the bright blue cresyl (BCB) test as an indirect method to select competent oocytes for the in vitro production of embryos (IVP). The cumulus-oocyte complexes (COC) were obtained from two Creole heifers subjected to two treatments: T1 = COC recovered by OPU (ovum pick-up) previous stimulation with FSH-LH; T2 = COC recovered from non-stimulated animals (control). The two heifers were alternated in the two treatments and five repetitions were done. Recovered COCs were classified into types A, B, C and D. Then the BCB test was applied to each of the COC types to determine if they were BCB+ or BCB-. T1 allowed to recover 5.2 more COC than T2 (p<0.05). When applying the BCB test, it was determined that all type A oocytes of T1 and T2 were BCB+; that is, they finished their growth and were ready to start the process of in vitro maturation; ...

El objetivo del presente estudio fue valorar la prueba del azul brillante de cresilo (BCB) como método indirecto para seleccionar ovocitos competentes para la producción in vitro de embriones (PIV). Los complejos cúmulos-ovocitos (COC) fueron obtenidos de dos vaquillas criollas sometidas a dos tratamientos: T1 = COC recuperados por OPU (ovum pick-up) previa estimulación con FSH-LH; T2 = COC recuperados sin previa estimulación de la donante (testigo). Las dos vaquillas fueron alternadas en los dos tratamientos y se hicieron cinco repeticiones. Los COC recuperados fueron clasificados en tipos A, B, C y D. Luego se aplicó la prueba del BCB a cada uno de los tipos de COC para determinar si son BCB+ o BCB-. T1 permitió recuperar 5.2 más COC que T2 (p<0.05). Al aplicar la prueba del BCB se determinó que todos los ovocitos tipo A de T1 y T2 fueron BCB+; es decir, terminaron su creci...