ABSTRACT. This study was conducted to compare the developmental competence of somatic nuclear transfer (NT) embryos, after either ionomycin or ethanol activation, in locally bred goats. Donor cells were prepared from the ear skin fibroblasts of a female goat. Cells, at passage 3-8, starved by culturing in 0.5% FCS for 4-8 d, were used for NT. Immature oocytes were obtained from FSH-stimulated goats and matured for 22 hr before enucleation and NT. After fusion, the reconstructed embryos were activated with either ionomycin or ethanol followed by culturing in 6-dimethylaminopurine (6-DMAP) and cytochalasin B (CB), for 3 hr. In experiment I, the fuse d NT embryos (n=63, ionomycin and n=68, ethanol treatments, respectively) were cultured in B 2 with a Vero co-culture system and their developmental competence was evaluated through to Day 9. In experiment II, the NT embryos at the 2-4 cell stage on Day 2 derived from each treatment (ionomycin n=46, and ethanol n=37), were transferred into 10 synchronous recipients. There were no significant differences between the NT embryos derived from the ionomycin and ethanol groups, in fusion (86.3% versus 82.9%), cleavage (90.5% versus 82.4%) and for morula/blastocyst development rates (9.5% versus 5.9%). Sixty percent (3/5) of the recipients from ionomycin became pregnant by midterm (2.5 mts) while only 20% (1/5) from ethanol treatment was pregnant by Day 45. The results demonstrate that activation with either ionomycin or ethanol in combination with 6-DMAP-CB treatment does not affect the development of cloned goat embryos. KEY WORDS: activation, developmental competence, goat, nuclear transfer.J. Vet. Med. Sci. 66(12): 1529-1534, 2004 Since the cloned sheep named "Dolly", was produced by transferring nuclei from adult cells into enucleated oocytes [27], there have been many studies carried out to produce other cloned mammals such as mice, cattle, goats, pigs and rabbits [1,5,19,25,26]. The nuclear transfer (NT) technique has been efficiently used for producing transgenic, cloned farm animal offspring. These animals are capable of producing valuable proteins, which could have a marked impact on the pharmaceutical industry [22] [1,4,6,11,32]. There are a few reports on the development of goat oocytes after parthenogenetic activation by treatment with ionomycin and ethanol, both followed by exposure to 6-diethylaminopurine (6-DMAP) [17,18]. Nevertheless, comparison of the development of NT goat embryos with either ionomycin or ethanol, as an activating agent, has not been reported. The objective of this study was to compare the developmental competence in vitro and in vivo of NT goat embryos, after activation, by using either ionomycin or ethanol, both followed by incubation in 6-DMAP-cytochalasin B (CB). MATERIALS AND METHODSUnless otherwise indicated, all chemicals used in this study were obtained from Sigma-Aldrich Company (St. Louis, MO) and the media from Gibco Invitrogen Corporation (Grand Island, NY).Preparation of donor cells: Donor cells were prepared from an ear skin f...