Inbred strains generated from native and exotic pigs were compared with their F 1 and F 2 backcross populations for a range of litter performance traits. Animals were intensively reared and at 81/2 months of age, the inbred genotypes from each strain were reciprocally mated to each other to generate F 1 crossbred genotypes; while gilts from each crossbred group were backcrossed to their male parents to obtain four backcross progeny groups. Results of the study showed that the litter performances were better in the crossbred groups than in the inbred parents and this improvement could be ascribed to the dominant genes from the exotic parents. Significant (P<0.05) heterosis was obtained in the crossbreds in most of the traits like prolificacy, nursing ability, sex-ratio, litter weight and gestation length. The heterosis observed in the litter traits was low and mostly non-significant. The backcross groups recorded residual heterosis in the litter traits monitored and the magnitude was higher in the exotic than in the native backcrosses. The results further indicate that the litter traits performance of the crossbred groups were mostly influenced by maternal, sex-linked, dominance and epistatic gene actions. It could be suggested that the litter traits of the native pig could be improved by cross-mating selected native and exotic backcross pigs. This could be followed by criss -crossing before group selection.

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Inbred strains generated from native and exotic pigs were compared for a range of pre-weaning and weaning letter performance traits. Animals were intensity reared and at 9 months of age, the inbred genotypes from each strain or breed were reciprocally mated to each other to generate F 1 cross bred genotypes. Results of the study showed that the Preweaning and weaning litter performances were better in the cross bred groups than in the inbred parents and this improvement could be ascribed to the dominant genes from the exotic parents. Significant (P<0.05) difference was obtained in the Perweaning and weaning birth weight, mortality rate, litter weight, litter growth rate, and litter weaning characteristics like litter size at weaning, survival rate to weaning, litter weight gain at weaning, litter mates weight difference at weaning and weaning sex ratio respectively. The superior performance of crossbred genotypes over the inbred were attributed to maternal, age and body weight of dam rather than genetic effects. The generally low reproductive performance of the present stock of pigs suggests the need to upgrade them by cross-mating selected native pigs with new imports.

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