Embryo production by in vitro fertilization of calf oocyte
1997
Mongkol Techakumphu | Chainarong Lohachit | Wichai Tantasuparak | Siriwat Suadsong | Jinda Singlor (Chulalongkorn Univ., Bangkok (Thailand). Faculty of Veterinary Science. Dept. of Obstetrics Gynaecology and Reproduction)
Embryo production by in vitro fertilization of prepubertal calf oocytes were studied. The calves aged 4-6 months were superstimulated by 192 mg follicle stimulating hormone (FSH) for 4 consecutive days (am/pm) in the reducing manner; 32/32, 24/24, 24/24, 16/16. The calves were repeated stimulated for 4 times. Sixty hours after the last FSH injection, the ovarian responses were examined and the oocytes were directly aspirated from growing follicles after caudal midline laparotomy. The oocytes were later matured and fertilized in vitro (IVF). After IVF, the embryos were either cultivated in vitro or transferred in ligated oviducts of sheep or rabbit doe for 6 days. Results showed that a high variation of responses among calves existed with the average of 31.9+-3.0 follicles per calf and the average oocytes per calf was 17.6+-1.8 which presented the recovery rate of 55.2 percent. A repeat stimulation tended to reduce the responses and the average number of recovered oocytes per donor significantly (P0.05). The in vitro maturation rate was 73.6 percent and the cleavage rate was 31.6 percent. The embryos can cleave in sheep or rabbit oviduct and developed to morula or blastocyst stage, however, it seemed that sheep oviduct was more appropriate to culture calf oocytes than rabbit oviduct. Subsequently, some of these embryos (20 percent) were able to develop in vitro after frozen-thawed. In addition, the oocyte collection by intravaginal ultrasound-guided aspiration (Ovum Pick Up) was developed and the technique applied for oocyte collection technique in a high genetic value calf. This study suggests a new track for cattle breeding improvement in the future by a reduction of generation interval, using prepubertal calf and in vitro fertilization and embryo transfer techniques.
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