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International audience; We performed a genome wide association study for growth and feed efficiency using the GEMMA software on 679 rabbits genotyped with the Affimetrix Axiom Rabbit 200K Genotyping Array. No significant SNP was found for growth traits or feed intake. Two and 89 chromosome-wide significant SNPs were detected for feed conversion ratio and residual feed intake, respectively. The 89 significant SNPs for residual feed intake were all located on chromosome 18, where the putative functional candidate gene GOT1 could be identified.

International audience; The aim of this study was to evaluate the significance of neonatal environment (ultimately including the microbiota composition) on feed efficiency. For that purpose, half of the rabbits of the G10 line, selected for 10 generations on residual feed intake (RFI), were fostered by does of a non-selected control line G0, and vice versa. In parallel, collaterals were adopted by mothers from their original line. Around 900 animals were produced in 3 successive batches and raised in individual or collective cages. Traits analyzed in this preliminary study were weights at weaning (32 days) and at the end of the test (63 days), average daily gain (ADG), feed intake between weaning and 63 days (FI), feed conversion ratio (FCR) and RFI. Line of the rabbit, type of housing (collective or individual cages: 2 levels) and batch (3 successive mating:3 levels) were significant effects for all traits. G10 does had a negative effect on FCR (+0.06, P=0.04), irrespective of the line of young rabbits. G10 animals were lighter than G0 at 32 days (-83 g) and at 63 days (-161 g). They also had a lower ADG (-2.36 g/day), FCR (-0.36), RFI (-548 g/day) and a lower FI (-839 g), confirming a better feed efficiency. Our results demonstrate that selection on feed efficiency was successful for direct effect but maternal effects were degraded by the selection. This study is part of the Feed-a-Gene Project, funded from the European Union’s H2020 Programme under grant agreement no. 633531.

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International audience; 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.

Le but du protocole présenté est d'évaluer l’importance de l’environnement néonatal (y compris le microbiote) sur l'efficacité alimentaire des lapins, et de quantifier l’effet de la transmission entre mère et jeunes sur ce caractère. Pour cela, des lapins de la lignée ConsR, sélectionnée pendant 10 générations sur la consommation résiduelle (CR), ont été adoptés par des mères de la lignée G0 à l’origine de cette sélection, et vice versa. En parallèle, des collatéraux étaient adoptés par des mères de leur lignée d’origine. 900 animaux ont été produits sur 3 mises bas successives, et élevés en cages individuelles ou collectives. Les caractères analysés dans cette étude préliminaire sont le poids au sevrage (32 jours), le poids en fin de test (63 jours), le gain moyen quotidien, la consommation d’aliment entre sevrage et 63 jours, l’indice de consommation (IC) et la CR. La lignée du lapereau, le type de logement et la bande ont des effets significatifs sur l’ensemble des caractères. La mère adoptive modifie significativement l’IC (P = 0,04), la mère adoptive ConsR ayant un effet défavorable similaire quelle que soit la lignée du lapereau. L’IC moyen des lapereaux de la lignée G0 adoptés par des femelles G0 est de 3,01 ± 0,03 et celui des lapereaux adoptés G0 par des femelles ConsR est de 3,05 ± 0,03. Pour les lapereaux ConsR adoptés par des femelles ConsR, l’IC moyen est de 2,69 ± 0,03 et pour les lapereaux ConsR adoptés par des femelles G0 l’IC moyen est de 2,63 ± 0,03., The aim of our design is presented ultimately to evaluate the significance of neonatal environment (including the microbiota) on feed efficiency rabbits, and quantify the effect of transmission between mother and young on that character. For this, the rabbits ConsR lineage, selected for 10 generations on residual consumption (CR), were adopted by mothers in the G0 line behind this selection, and vice versa. In parallel, collateral were adopted by mothers from their original lineage. 900 animals were put products on 3 successive low and high in individual or collective cages. The characters analyzed in this preliminary study are weight at weaning (32 days), the end of the test weight (63 days), average daily gain, feed intake between weaning and 63 days, feed efficiency ( IC) and CR. The lineage of the rabbit, type of housing and the band have significant effects on all the characters. The adoptive mother significantly alter the IC (P = 0.04), the adoptive mother ConsR with a similar adverse effect regardless of the line of rabbit. The average IC young rabbits the G0 line adopted by G0 females is 3.01 ± 0.03 and that of the young rabbits adopted by G0 ConsR females is 3.05 ± 0.03. For rabbits ConsR adopted by ConsR females, the average IC is 2.69 ± 0.03 and for rabbits ConsR adopted by G0 females the average IC is 2.63 ± 0.03.

Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access; Genetic parameters of feed efficiency and growth traits were estimated in two selected rabbit lines after 6 generations of selection. The ConsR line was selected for residual feed intake (RFI) under ad libitum feeding. The AlimR line was selected for average daily gain (ADG from 30 to 63 days) under restricted feeding corresponding to 80 % of ad libitum feed intake of control animals. Estimates of heritability of ADG and FCR (feed conversion ratio) were higher in the AlimR line than in the ConsR line, while estimates of heritability of weight at 30 and 63 days-old were similar between lines. Heritability of ADG (0.25), the selection criterion of the AlimR line, was higher than RFI (0.15), the selection criterion of the ConsR line. Estimates of heritability and genetic correlations between weaning weight, weight at 63 days, ADG and FCR are also presented for each line.

Genetic parameters of feed efficiency and growth traits were estimated in two selected rabbit lines after 6 generations of selection. The ConsR line was selected for residual feed intake (RFI) under ad libitum feeding. The AlimR line was selected for average daily gain (ADG from 30 to 63 days) under restricted feeding corresponding to 80 % of ad libitum feed intake of control animals. Estimates of heritability of ADG and FCR (feed conversion ratio) were higher in the AlimR line than in the ConsR line, while estimates of heritability of weight at 30 and 63 days-old were similar between lines. Heritability of ADG (0.25), the selection criterion of the AlimR line, was higher than RFI (0.15), the selection criterion of the ConsR line. Estimates of heritability and genetic correlations between weaning weight, weight at 63 days, ADG and FCR are also presented for each line.