Commercial Production of Bovine Embryos In Vitro from Prepubertal Dairy Cattle Oocytes(Thai)

Abstract

This experiment was carried out to explore the possibility of utilizing prepubertal calf oocytes as a source to produce bovine blastocysts in vitro. Ten female calves (age 4-6 months old) received follicle stimulating hormone (FSH) at the dose of 50 mg/calf. At 24 h after the last FSH injection, laparotomy was performed to collect immature oocytes from ovarian follicles. The total number of follicles identified with diameter of 1-2 mm, 3-4 mm, 5-6 mm, and 7-8 mm were 58, 62, 17 and 6 respectively. Follicular aspiration was conducted to collect the immature oocytes. A total of 60 oocytes was recovered and classified as 34 complete cumulus oocyte complexes, 3 incomplete cumulus oocyte complexes, 3 oocytes with cumulus expansion, 1 nuded oocyte and 20 degenerated oocytes. Only good quality oocytes were selected for further culture to complete the maturation process. For in vitro maturation, oocytes were cultured in TCM-199 medium supplemented with FSH 0.5 ug/ml, LH 10 ug/ml and estradiol 17- 1 ug/ml under 5% CO2 in air at 39 °C for 18-24 h. After in vitro fertilization, the numbers of embryos that developed to the 2 - cell stage, 4 - cell stage, and 8 - cell stage were 7, 7 and 10 respectively. None of these embryos were able to develop beyond the 16 cell stage. The results of this study show that, under our conditions, oocytes recovered from prepubertal calves (4-6 month old) were not suitable for producing bovine blastocyst in vitro.