Crossbreeding parameters for growth and feed consumption traits from a five diallel mating scheme in rabbits

Twenty-five genetic groups of young rabbits originated from a diallel-crossbreeding scheme among 5 selected lines: 3 maternal and 2 terminal sire lines belonging to 2 Spanish research institutions. A sample of 2,773 young rabbits from 525 litters was controlled during the fattening period lasting from 5 to 9 wk. Growth and feed consumption traits were evaluated throughout different biweekly batches. A Bayesian approach was used for inference from an animal model with common litter effects. On average, genetic groups coming from lines selected for growth rate were heavier (+58.9 g at 32 d and +315.5 g at 60 d), had greater growth rate (9.24 and 8.15 g/d from individual or cage analysis, respectively) and feed intake (+13.24 g/d), and showed better feed conversion ratio (-0.21 g of intake/g of gain), than the genetic groups originated from crosses among lines selected for litter size. Crossbreeding parameters were estimated from the samples of the marginal posterior distribution of the genetic group effect according to the Dickerson model. Maternal genetic and individual heterosis effects were null or very low. Direct genetic effects mainly regulated the expression of growth traits.