GENERAL AND SPECIFIC COMBINING ABILITY OF GROWTH PERFORMANCE ATTRIBUTES IN RABBITS

This work aimed to estimate general (GCA) and specific (SCA) combining ability and reciprocal crosses (RC) effects on rabbit growth performance attributes from weaning to marketing to recognize the best suitable crossbred for rabbit breeder to use in rabbit meat production under Egyptian circumstances. A total of 123 male (59) and female (64) rabbits represents three breeds and their diallel crosses were used in this study. The pure breeds were New Zealand White (N), Papillon (P) and Flemish Giant (F). The six crossbreeds were NF, NP, FP, FN, PN, PF. The growth performance attributes were body weights at 4 (BW4), 8 (BW8) and 12 (BW12) weeks of age, daily weight gain between 4 and 8 weeks (DG4-8), 8 and 12 weeks (DG8-12) and between 4 and 12 weeks (DG4-12) and relative growth rate (RG) at the same interval ages (RG4-8, RG8-12 and RG4-12). The present results showed positive interrelationship among all body weight traits. However, BW8 was highly correlated with DG at all studied ages (r=0.61 to 0.91). There is highly negative correlation between BW4 and RG at 4-8wks and 4-12 wks of age. The genotype had significant effect on body weight at 8 and 12 weeks of age. N rabbits were recorded to be the heaviest breed at weaning (4 weeks), while PN and FN crosses were recorded to be the heaviest rabbits at market (12 weeks). Genetic groups were found to had highly significant effect on DG and RG, during all intervals age. On the other hand, effect of sex on BW, DG and RG of growing rabbits were not significant at studied intervals. Insignificant effect for GCA, SCA and RC on BW were recorded at different ages, except for the reciprocal cross effect at 12 weeks of age. The NP crossbred seemed to be the best cross combination in improving of BW. GCA, SCA and RC had significant effect (P < 0.05 or 0.001) on DG and RG. FN crossbred was found to be the best 200 KARIMAN FARG et al. genetic group among all crosses for DG and RG. Conclusively, the results obtained in present study suggested that Papillon is a promising breed in crossbreeding program regarding growth performance traits. Crossing of New Zealand White as a sire breed with Papillon as a dam breed, NP, would be recommended over other crosses to improve marketing weight in rabbits. However, Crossing of Flemish Giant as a sire breed with New Zealand White as a dam breed, FN, would be recommended over other crosses to improve growth rates in rabbits especially in case of marketing rabbits at constant weight to save time and cost.