OC12 Combination of IVF Strategies to Reduce Porcine Polyspermic Fertilization: Straw IVF System and Short Gamete Coincubation Time

Abstract

This study was conducted to evaluate the combined effect of a short period of gamete coincubation and a new in vitro fertilization (IVF) system in straw (Li et al., 2003; Biol. Reprod. 69: 1580) to attempt to reduce polyspermic penetration. A total of 723 in vitro matured oocytes were inseminated with thawed spermatozoa. Various sperm concentrations (20 000, 30 000, 40 000, and 50 000 sperm/oocyte) and two coincubation times (6 h and 10 min) were used for straw‐IVF and compared to control group (1000 sperm/ovocito, in microdrop). The oocytes from 10 min group were washed in mTBM medium to remove spermatozoa not bound to the zona and transferred to the same medium (containing no sperm) for 6 h. After 6 h, oocytes from each group were cultured in NCSU‐23 medium for 12–15 h to assess fertilization parameters. The sperm concentration did not affect the efficiency of the IVF in both periods of coincubation. The short coincubation time significantly (p < 0.001) increased penetration rate and efficiency of the IVF (67.7 ± 6.4% vs 31.19 ± 6.5% and 41.5 ± 2.5% vs 17.6 ± 2.5% for 10 min and 6 h, respectively), while there were no significant differences in the incidence of monospermy between 10 min (64.3 ± 5.1) and 6 h (67.7 ± 3.4%) coincubation times. The penetration rate in the control group was higher (95.5 ± 5.6%; p < 0.001) than in the straw groups, but monospermy was severely reduced (25.0 ± 4.3%). These results show that short coincubation time together with the straw IVF system improves the efficiency of the porcine IVF. (Supported by SENECA).