Housing Conditions, Level of Feeding and Presence of Antibiotics in the Feed Shape Rabbit Cecal Microbiota

Background: the effect of the production environment and different management practices in rabbit cecal microbiota remains poorly understood. While previous studies have proved the impact of the age or the feed composition, research in the housing conditions and other animal management aspects, such as the presence of antibiotics in the feed or the level of feeding, is still needed. Characterization of microbial diversity and composition of growing rabbits raised under different conditions could help better understand the role these practices play in cecal microbial communities and how it may result in different animal performance. Results: Four hundred twenty-five meat rabbits raised in two different facilities, fed under two feeding regimes ( ad libitum or restricted) with feed supplemented or free of antibiotics, were selected for this study. A 16S rDNA-based assessment through the MiSeq Illumina sequencing platform was performed on cecal samples collected from these individuals at slaughter. Different univariate and multivariate approaches were conducted to unravel the influence of the different factors on microbial alpha diversity and composition at phylum, genus and OTU taxonomic levels. The animals raised in the facility harboring the most stable environmental conditions had greater, and less variable, microbial richness and diversity. Bootstrap univariate analyses of variance and sparse partial least squares-discriminant analyses endorsed that the farm exerted the largest influence on rabbit microbiota since the relative abundances of many taxa were found differentially represented between both facilities at all taxonomic levels characterized. Furthermore, only five OTUs were needed to achieve a perfect classification of samples according to the facility where animals were raised. The level of feeding and the presence of antibiotics did not modify the global alpha diversity but had an impact on some bacteria relative abundances, albeit in a small number of taxa compared with the farm, which is consistent with the lower sample classification power according to these factors achieved using microbial information. Conclusions: this study reveals different degrees of influence attributable to environment and animal management. It highlights the importance of offering a controlled breeding environment that reduces differences in microbial cecal composition that could be causative of different animal performance.