Effect of Non Breeding Season on Oocyte Recovery from Superovulated Korean Native Goats

This study assesses of efficiency of oocyte recovery and in vitro development for during the non breeding season in goat. Thirty-four matured goats, maintained in a pen under natural day length and fed hay ad libitum, were pretreated with progestagen implanted CIDR for 10 days. Superovulation treatment of the goats received twice daily intramuscular injections of a total of 70 mg FSH for 3 days from Day 8 of CIDR. All the gonadotropin treated goats were injected with 10 mg $PGF_2{\alpha}$ on Day 8 and 400~600 IU hCG in the afternoon on Day 10. Oocytes were recovered by follicle aspiration or oviduct flushing at 35 to 40 h after hCG injection through mid-ventral incision. The in vivo matured oocytes were activated by ionomycin (5 min) and 6-DMAP (3.5~4 h). The activated oocytes were cultured in mSOF medium containing 0.8% BSA at $38.5^{\circ}C$ in an atmosphere of 5% $CO_2$, 5% $O_2$, 90% $N_2$ for 7~8 days. There was no significant difference in the mean number of CL and in vivo matured and follicular oocytes recovered. But, quality of I+II grade follicular oocytes was lower (p<0.05) in the prepubertal goat (25.0%) than the adults (52.4%). The same results were also observed in the cleavage and blastocyst rate of activated oocytes. The clavage and blastocyst rate from prepubertal derived oocytes were lower (p<0.05) in the prepubertal goat (54.5%, 23.3%) than the adult goat (86.8%, 46.6%). Considering overall these results, we suggest that maturation of donor goats is a major factor affecting recovered oocytes quality and in vitro development of activated goat oocytes. There was no significant difference in oocyte quality between seasonal treatments.

재래산양의 비번식기에 과배란 처리에 의한 난자 회수와 단위발생란의 체외발달

본 연구는 연중 비번식기에도 효율적인 재래산양 난포란의 확보가능성을 검토하고자 비번식기에 과배란 처리를 실시하여 체내 성숙난자 및 난포란을 회수하였으며, 회수란의 활성화를 유도하여 체외발달율을 조사하였다. 비번식기에 과배란 처리에 의한 배란점은 각각 $13.9{\pm}6.5$개로서, 번식의 $13.0{\pm}3.8$개와 차이가 없었다. 난관에서 외과적 관류방법으로 체내성숙난자를 회수하였을 회수율은 43.9%로서 번식기의 67.1%보다 낮았다(p<0.05). 공란 산양 두당 회수 난자수는 비번식기가 $5.9{\pm}5.2$개로서, 번식기의 $8.8{\pm}3.2$개보다 적었다. 공란 산양으로부터 체내 성숙난자 회수 후 난소의 난포로부터 주사기로 흡입하여 채란 시에 공란 산양 두당 난포수는 비번식기가 $5.8{\pm}4.6$개로서 번식기의 $7.5{\pm}3.9$개보다 적었으며(p<0.05), 회수율은 각각 68.7 및 54.7%로서 차이가 없었다. 공란 산양 두당 회수난자 수도 $3.9{\pm}3.2$ 및 $4.1{\pm}3.4$개로서 차이가 없었다. 회수한 난포란의 등급도 비번식기와 번식기간에 차이가 없었다. 비번식기에 회수한 체내성숙 난자를 단위발생을 유도하였을 때 분할율은 76.4%로서 번식기의 83.6%와 차이가 없었으며, 배반포기로의 발달율은 비번식기가 23.8%로서 번식기의 43.5%보다 유의적(p<0.05)으로 낮았다.