Development of goat embryos after in vitro fertilization and parthenogenetic activation by different methods

Effective activation protocols that can be used during nuclear transfer inv estigations in goats need to be developed. We compared the development of I VF goat embryos with those of nonfertilized parthogenetically developing oo cytes activated by treatment with either ionomycin or ethanol, both followe d by immediate exposure to 6-diethylaminopurine (6-DMAP). Cumulus oocyte co mplexes (COCs) recovered from abattoir goat ovaries were either matured in a conventional laboratory incubator or placed in pre-equilibrated maturatio n medium and shipped overnight in a battery-operated dry incubator to anoth er laboratory. Mature COCs were allocated randomly to one of three treatmen t groups. Group I oocytes (n=169 shipped, n=253 not shipped) were fertilize d in vitro at 24 h postmaturation (hpm). The remaining COCs were activated at 28 hpm in either ionomycin (Group 2: n=362 shipped, n=202 not shipped), or ethanol (Group 3: n=263 shipped, n=249 not shipped). Activated oocytes w ere immediately incubated in 6-DMAP for 4 h. Blastocyst development was eva luated on Day 8 postinsemination/activation. Percent cleavage was comparabl e in shipped and nonshipped oocytes and in all treatment groups. In both sh ipped and nonshipped oocytes, parthenotes developing from ionomycin- and et hanol-activated oocytes had significantly greater blastocyst development (P <0.01) compared to IVF embryos (28.5 +/- 3.0, 27.4 +/- 2.8, 10.3 +/- 3.0, respectively for the nonshipped oocytes and 9.9 +/- 2.1, 10.3 +/- 2.4, 3.7 +/- 4.7 respectively for the shipped oocytes). Shipped oocytes had lower bl astocyst development compared to nonshipped oocytes in the three treatment groups. The mean blastocyst cell number was not statistically different bet ween shipped and nonshipped oocytes or among treatment groups, suggesting t hat ail were equally viable. (C) 2001 by Elsevier Science Inc.