Birth of Calves Derived from Oocytes Collected by Transvaginal Ultrasound Guided Follicular Aspiration

Abstract

Follicular oocytes were collected from FSH-stimulated (n=15) and unstimulated (n=14) cows by ultlrasound-guided follicular aspiration. The mean number of aspirated follicles (≤2 mm) was significantly (P<0.05) higher in FSH-stimulated (13.7) than in unstimulated (8.5) cows. There was no significant difference in the mean number of recovered oocytes between FSH-stimulated (7.3) and unstimulated (5.6) cows. The proportions of oocytes that cleaved and developed to the morula/blastocyst stage were 53 and 23% for FSH-stimulated and 44 and 12% for unstimulated cows, respectively, indicating no significant differences between the 2 groups. Two calves were born after transfer of 8 embryos originating from FSH-stimulated cows, and one set of twins was born after the transfer of 3 embryos originating from unstimulated cows. In another experiment, oocytes were aspirated weekly for one month from 5 unstimulated cows. A total of 10 to 41 oocytes were collected from each cow, and some of them were developmentally competent in vitro after in vitro maturation and fertilization. No detrimental effects were observed in these cows by clinical and postmortem examinations.