Successful piglet production by IVF of oocytes matured in vitro using NCSU-37 supplemented with fetal bovine serum

Recently, piglets have been obtained from in vitro-produced blastocysts by using in vitro maturation systems in which oocytes have been matured in North Carolina State University (NCSU) solution supplemented with porcine follicular fluid (PFF). However, PFF is not available commercially. To prepare PFF from the ovaries required time and effort and there is substantial variation in quality among batches. Furthermore, PFF is considered a potential source of infectious agents. We evaluated another commercially available potential protein source, fetal bovine serum (FBS), for in vitro maturation, to produce embryos and piglets. Cumulus–oocyte complexes were matured in NCSU-37 with PFF or with one of four batches of FBS. The proportions of oocytes with expanded cumulus cells were lower in all FBS batch groups ( P < 0.05, 15–41%) than that in the PFF group (74%). The proportions of oocytes that matured were also lower in all FBS batch groups ( P < 0.05, 26–41%) than in the PFF group (73%), irrespective of cumulus expansion. However, the proportions of oocytes that underwent germinal vesicle breakdown were almost the same in all groups (76–96%). After in vitro fertilization, the rate of sperm penetration into matured oocytes was higher in the PFF group ( P < 0.05, 63%) than in one batch of FBS (22%) and removal of the compacted cumulus cells after maturation did not affect fertilization status (21%). Subsequent in vitro embryo culture of the PFF and FBS groups for 6 day resulted in similar rates of blastocyst formation (17 and 19%, respectively) and similar numbers of cells per blastocyst (43 and 46 cells, respectively). When blastocysts obtained from oocytes matured with FBS were transferred into two recipients, one became pregnant and farrowed seven piglets. Transfer of blastocysts obtained from oocytes matured with PFF into two other recipients resulted in one pregnancy and production of four piglets. These data suggested that porcine in vitro maturation in NCSU-37 supplemented with FBS reduced the maturational ability of oocytes, but once oocytes have matured, they have the same ability to develop to term after in vitro fertilization and embryo transfer as those matured with PFF.