Bovine ovaries (paired by cow) were obtained from a local abattoir and cumulus oocyte complexes were aspirated within six hours of slaughter. Two methods for activation [(1) calcium ionophore (ionomycin) alone (n = 191); and (2) ionomycin followed by the protein synthesis inhibitor cycloheximide (n = 207)] were evaluated for production of bovine parthenogenones. Activation with ionomycin alone resulted in a development rate of 33%, while activation with ionomycin and cycloheximide sequentially resulted in a development rate to two-cell stage of 49%. A procedure was developed to expedite accurate evaluation of activated oocytes for uniformly haploid development. Uniformly haploid parthenogenones that cleaved at least once in four days of in vitro culture were individually prepared for genetic analysis. Three techniques: (1) phosphate buffered saline; (2) TL-HEPES with 0.2% ovine serum albumin; and (3) TL-HEPES with 0.2% polyvinyl pyrrolidone were compared to harvest parthenogenones for genetic analysis. The only effective method that did not create spurious results during later genetic analysis was TL-HEPES with 0.2% polyvinyl pyrrolidone. Based on the results of this study, we estimate that an average of 5-7 uniformly haploid bovine parthenogenones can be realized from each donor (using pairs of ovaries). These parthenogenones, when maintained as family units, will be valuable for accomplishment of female-specific genetic linkage analysis.

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A series of mouse lines was produced by long-term restricted index selection for divergent rate of growth during early and late postnatal development. The selection program was based on the following treatments: E+ and E- lines were selected to alter birth to 10-day weight gain while holding late gain for both lines constant and a control line was established via random selection. Using embryo transfer and crossfostering methodology, we partitioned postnatal growth for E+, E-, and C lines into progeny genetic, uterine maternal, and nurse maternal components. Selection for differential early growth resulted in correlated response in uterine and nurse maternal effects on body weights, with significant genetic-by-environment interactions. Significant uterine effects were also observed in tail length measurements. Direct uterine effects on body weight were relatively small and resulted in growth rate differences early in development. Nurse effects were large, resulting in modification of progeny growth trajectory especially during early postnatal development. Genetic-by-uterine interactions were large and demonstrate progeny-specific effects of the prenatal uterine environment.