PARENT SESSION
FERTILIZATION
Harborside C
7:30 AM-10:00 AM

(523) EFFECT OF IN VITRO FERTILIZATION OF PIG OOCYTES MATURED IN DIFFERENT IN VITRO MATURATION MEDIA ACCORDING TO SPERM CONCENTRATIONS OF LIQUID BOAR SEMEN.

Park, Chang-Sik¹, Yi, Young-Joo¹, ¹ Division of Animal Science and Resources, Daejeon, KR

ABSTRACT- The present study was carried out to investigate the effects of maturation media on penetrability of pig oocytes by liquid boar sperm coincubated with different sperm concentrations in a modified Tris-buffered medium (mTBM). Follicular oocytes collected from ovaries of prepubertal gilts were matured in a mTCM-199 medium, mWaymouth MB 752/1 medium or NCSU-23 medium. Oocytes (30-40) were transferred into each well of a Nunc 4-well dish containing 0.5 ml maturation medium. The sperm-rich portion of ejaculates with greater than 90% motile sperm were used. The semen was diluted with Beltsville Thawing Solution (BTS) extender at room temperature to give 2×10⁸ sperm/ml in 100 ml plastic bottle. Liquid boar semen of 30 ml in the bottle was kept at 17°C for 5 days. The sperm with greater than 70% motility after day 5 of storage were used for in vitro fertilization (IVF). After 44 h maturation of immature oocytes in 5% CO₂ in air at 38.5°C, cumulus cells were removed and oocytes (30-40) were coincubated for 6 h in 0.5 ml mTBM fertilization medium with five different (1×10⁶, 2×10⁶, 4×10⁶, 6×10⁶, 10×10⁶/ml) sperm concentrations. At 6 h after IVF, oocytes were transferred into 0.5 ml NCSU-23 culture medium for further culture of 6 h. At 12 h after IVF, sperm penetration, polyspermy and male pronuclear formation of oocytes were evaluated. Oocytes of NCSU-23 maturation medium decreased polyspermy and increased male pronuclear formation compared to those of mTCM-199 and mWaymouth MB 752/1 maturation media. Oocytes matured in NCSU-23 medium and inseminated in mTBM medium with 2-4×10⁶/ml sperm concentrations showed 50.8-50.9% sperm penetration, 13.3-19.5% polyspermy and 43.9-45.4% male pronuclear formation. In conclusion, we found out that oocytes matured in NCSU-23 medium and inseminated in mTBM medium showed superior IVF results compared to those matured in mTCM-199 and mWaymouth MB 752/1 maturation media and inseminated in mTBM medium. The optimum sperm concentrations for IVF of oocytes matured in NCSU-23 medium by liquid boar semen stored at 17°C for 5 days were 2-4×10⁶/ml.

KEY WORDS: In vitro fertilization, pig oocytes, maturation, sperm concentration