Efecto de la estimulación de ondas foliculares con eCG sobre la producción in vitro de embriones, en vacas Bos indicus

Abstract

This study analysed the effect of follicular wave stimulation with equine chorionic gonadotrophin (eCG) on the follicular population, oocyte competition and in vitro production of embryos (IVEB) in Bos indicus cows of the Gyr line. The aim was to determine the follicular response during the first and second waves, to compare the number and quality of oocytes retrieved with and without hormonal stimulation, and to evaluate its effect on embryonic development. The sample consisted of four Gyr crossbred cows, with one to three calvings, divided into two treatment groups: two animals received 600 IU of eCG two days before each follicular aspiration, and two formed the group without eCG. The aspirations by OPU were carried out on days 4 and 14 of the oestrous cycle, and the cumulus-oocyte complexes were evaluated and subjected to maturation, fertilisation and in vitro embryo culture. The results showed a numerically favourable response with eCG: the mean follicle size in the left ovary increased from 6.75 mm to 8.75 mm; the mean total number of viable embryos, from 1.25 to 3.75; and the mean number of blastocysts, from 0.25 to 2.50. In total, 15 viable embryos were obtained with eCG compared with 5 without eCG. The differences between treatments were not statistically significant (p>0.05), except in the supplementary analysis of viable embryos. It was concluded that the administration of 600 IU of eCG two days prior to OPU numerically favoured follicular response and embryo production, although its effect on embryo quality was inconclusive.