This study was conducted to investigate the efficacy of vitrification procedure for the cryopreservation of porcine oocytes and the utilization of vitrified oocytes as recipient cytoplasts for somatic cell nuclear transfer (NT), and observed that porcine oocytes are evaluated by pronuclear formation, and parthenogenetic development. Single fetal donor cells were deposited into the perivitelline space of vitrified enucleation oocytes, followed by electrical fusion and activation. NT embryos were cultured in NCSU-23 medium supplemented with 5% FBS, at in 5% and air. 1. When the developmental rates of the oocytes after being culture for hours vitrified with EDS and ETS were 42.0%, 38.0%, respectively. This results were lower than the control group(62.2%). 2. When the developmental rates of the oocytes after being culture for hours vitrified-thawed with sucrose and glucose, 5% PVP, NCSU-23 supplemented with 10% FBS were 33.3%, 25.9%, respectively. This results were lower than the control group(55.6%). 3. The fusion and development to the blastocyst stage between the NT embryos constructed with the vitrified and non-vitrified oocytes were significant differences. Developmental rate of oocytes and NT embryos constructed with the vitrified or non-vitrified oocytes were , respectively.

This study was carried out to find out the changes on serum concentrations of estradiol-17β, progesterone in primiparous Duroc, Landrace and Yorkshire sows weaned at 7 or 21 days. Also, we compared the litter size at birth and weaning among the breeds weaned after lactation for 7 or 21 days. The estradiol-17β concentrations among the breeds were 6.9∼8.8 pg/ml and 6.4∼8.8 pg/ml after lactation for 7 or 21 days, respectively. The progesterone concentrations ranged from 0.3 ng/ml to 1.6 ng/ml. Duroc sow showed higher progesterone concentration compared with Landrace and Yorkshire sows weaned after lactation for 7 or 21 days. Also, we found out that litter size at birth and weaning, respectively, did not show any differences between day 7 and day 21 of lactation. From the facts mentioned above, it was suggested that very early weaning systems could work with no apparent adverse effect on prolificacy.