156 OVIDUCTAL FLUID SUPPLEMENTATION DURING MATURATION AND FERTILIZATION IMPROVES IN VITRO EMBRYONIC DEVELOPMENT IN PIGS

Abstract

Oviducal fluid has a major role in the maturation of gametes and the process of fertilization. The objective of this study was to determine the effects of oviducal fluid supplementation in vitro, during oocyte maturation and IVF on fertilization characteristics and early embryonic development rates. Oocytes from aspired aspirated mature follicles (3–6 mm diameter) were obtained from a local abattoir. During the last 24 h of maturation, oocytes (n = 1303) were placed into maturation media supplemented either 1% (vol/vol) or 5% (vol/vol) thawed snap-frozen oviducal fluid. Fertilization was performed using pooled frozen-thawed semen from 3 different boars. During IVF, the fertilization medium was supplemented with 1% (vol/vol) or 5% (vol/vol) oviducal fluid. Fertilization characteristics were evaluated 12 h after IVF and rates of embryonic cleavage and blastocyst development were observed at 48 and 144 h after IVF, respectively. Data were analysed using ANOVA with the main effects including treatment, well, and replicate. Chi-square analysis was used to determine percentages of embryos reaching the different developmental stages for each treatment. There were no significant differences in the percentages of oocytes that reached metaphase II by the end of maturation or in sperm penetration rates after IVF. However, oocytes treated with 1% (vol/vol) oviducal fluid during the end of maturation and IVF (33.33 ± 2.61) and 5% (vol/vol) oviducal fluid during maturation (33.33 ± 2.66) or IVF (39.53 ± 3.78) had significantly less (P < 0.05) incidence of polyspermic penetrations and a significantly higher (P < 0.05) incidence of male pronuclear formation (87.50 ± 4.01; 86.67 ± 4.83; 86.05 ± 3.19, respectively) compared with no oviducal fluid supplementation. Oocytes supplemented with 5% (vol/vol) oviducal fluid during maturation and IVF had significantly lower (P < 0.05) incidences of polyspermic penetration (27.91 ± 2.50) and significantly higher (P < 0.05) percentages of embryos reaching the 2-cell stage (81.76 ± 3.72) and blastocyst stage of development (37.74 ± 1.09) by 48 and 144 h, respectively, compared with all other groups. The results of this study suggest that supplementing 5% (vol/vol) oviducal fluid during maturation and IVF improves the success rates of in vitro embryo development in pigs.