Selection for residual feed consumption in the rabbit

We carried out a one-generation, divergent selection experiment on residual feed efficiency in order to estimate the genetic parameters of this trait. The selection criterion was the residual feed consumption. We measured the consequences of this selection on growth, feed efficiency, and carcass composition. One generation of selection was performed on young male rabbits from a heavy weight line. They were individually caged and measured for their weight gain and feed consumption between weaning (30 days) and 65 days of age. The fatness of all the males was estimated by ToBEC measurement (Total Body Electrical Conductivity) at 65 days of age. Their offspring were bred under the same conditions and 120 males were slaughtered at 65 days of age in order to estimate the correlated response on carcass traits: dressing yield, cutting parts, fatness, ultimate pH, and colour. Genetic parameters were estimated with restricted maximum likelihood applied to an animal model. The heritability value estimated for residual feed consumption was 0.45±0.11, which was of the same order as the heritability estimated for average daily gain (0.41±0.13) and higher than the heritability estimated for the feed conversion ratio (0.27). Residual feed consumption was negatively correlated with the hind part percentage (−0.71) and correlated positively with front part percentage (0.54). The genetic correlations with dressing percentage and carcass fatness were very low. Residual feed consumption may be introduced as a selection criterion for improving feed efficiency. Thus, no significant phenotypic differences were found between offspring of high and low residual feed consumption males, except for the hind part percentage, which was higher in the low residual feed consumption line.