Performances of growing rabbits are determined by their genotype and their environment. The effect of maternal environment is particularly important in this species. Improvement of feed efficiency is essential to increase the competitiveness of the rabbit industry but also to reduce the animal excretion, and consequently decrease the environmental impact of the production. It can be achieved in rabbit by selection on residual feed intake (RFI) or on growth under restricted feeding (Drouilhet et al., 2013, 2015). However, these selection strategies do not take into account the contribution of gut microbiota to improved feed efficiency, although some previous results have demonstrated its relation with digestive efficiency in chicken (Mignon-Grasteau et al., 2015). To further investigate the effects of the animal genotype and maternal environment on feed efficiency, an experiment based on cross fostering between a line selected on RFI and a non-selected control line was performed. Ultimately, it should allow disentangling the effect of animal genetic and dam microbiota transmission on the traits. The objective of this preliminary study was to estimate both host genotype effect and maternal environment effect on growth and feed efficiency in rabbit.