Crossbreeding parameters for body weight data from a complete diallel mating scheme using three breeds of rabbit

The objective of this study was to evaluate heterosis, general combining ability (GCA), maternal ability ( $G^M$ ), and sex-linked effects (SL) for growth performance from weaning (at 4 weeks) up to marketing age (at 12 weeks) using a complete $3\times 3$ diallel crossing experiment in three different breeds of rabbit: one native Egyptian (Baladi Red, RR) and two exotic (Bauscat, BB, and Californian, CC). Offspring (2617 rabbits) body weight data (BW; 4-12 weeks of age) were analyzed, mainly to evaluate the effects of mating groups (MGs), sex, year season, and parity. MGs were further analyzed for crossbreeding parameters. All crossbreds showed positive, highly significant values ( $P\le 0.001$ ). Heterosis ( $H^I$ ; overall or specific) for body weight at all evaluated ages was highly significant ( $P\le 0.001$ ). Purebred differences were affected significantly ( $P\le 0.01$ or $P\le 0.001$ ). No significant effects were detected due to general combining ability, maternal abilities, or reciprocal effect (sex-linked). Results suggest that to some extent and because of the highly purebred significant differences ( $P\le 0.01$ or $P\le 0.001$ ), those three breeds are expected to be too genetically far apart to make crosses showing significant heterosis. Since other crossbreeding effects are non-significant, heterosis is the only reliable effect that can produce the Egyptian broiler rabbits when using those three breeds. However, the insignificance of the reciprocal impact (sex-linked as a whole or, by definition, the additive effects of genes carried on the sex chromosomes) of the two acclimatized standard breeds (CC and BB) seemed to be of magnitude at least to the 10th week of age.