The Effects of Different Oocyte Maturation Media on the Production of in Vitro Derived Pig Embryos

Polyspermic penetration in pig oocytes has been identified as a persistent problem during in vitro fertilization (IVF) within the swine industry. The composition of oocyte maturation media has an affect on successful cytoplasmic and nuclear maturation of the oocyte. The objective of this study was to determine the effects of the meiosis inhibitor, dibutyryl-cAMP (dbcAMP), and media formulation on oocyte maturation and subsequent IVF and embryo culture success. Oocytes (n = 656, r = 3) were matured in either a modified Medium 199 (M199) or a porcine oocyte maturation media (POM) for 48 h and either with dbcAMP supplemented to the media for the first 24 h of maturation or not. Oocytes were evaluated for nuclear maturation (n = 130). Oocytes (n = 526) were fertilized using frozen-thawed semen and evaluated for fertilization characteristics and subsequent embryonic development at 48 h and 144 h for cleavage and blastocyst formation, respectively. Oocytes matured in M199 and dbcAMP had a significantly higher (P < 0.05) percentage of oocytes reaching metaphase II (MII) by 48 h (83.33% ± 3.34) compared to those matured in POM and dbcAMP (66.67% ± 4.78). The addition of dbcAMP during the first 24 h caused a significantly higher (P < 0.05) percentage of oocytes reaching MII by 48 h compared to no dbcAMP supplementation in both M199 (58.26% ± 5.23) and POM (32.26% ± 5.98). Oocytes matured in POM with dbcAMP had significantly fewer (P < 0.05) penetrated oocytes 12 h after IVF compared to all other treatment groups. Oocytes matured in M199 had significantly fewer (P < 0.05) polyspermic oocytes 12 h after IVF compared to those matured in POM. Oocytes matured with dbcAMP supplementation for the first 24 h of maturation had significantly higher (P < 0.05) male pronuclear formation compared to those not supplemented with dbcAMP. There were no significant differences between the treatment groups with respect to embryo cleavage 48 h IVF. Oocytes maturated in M199 media had a significantly higher (P < 0.05) percentage of those reaching the blastocyst stage of development by 144 h after IVF compared to oocytes maturated in POM. The results indicate that oocytes matured in M199 and supplementation with dbcAMP during the first 24 h of maturation have the greatest success in developing in vitro derived embryos.