Postnatal development of the rabbit caecal microbiota composition and activity.
This study describes the development of the rabbit caecum microbiota and its metabolic activities from the neonatal (day 2) until the subadult period (day 70). The caecal microbiota was analysed using 16S rRNA gene approaches coupled with capillary electrophoresis single-stranded conformation polymorphism (CE-SSCP) and qPCR. At day 2, rabbits harboured population levels up to 8.4, 7.2 and 7.4 log(10) copy number g(-1) full caecum of the total bacteria, Bacteroides-Prevotella and Firmicutes groups, respectively. These populations reached their maximum levels from day 14 for Firmicutes groups (10.8 log(10) copy number g(-1) caecal content) and day 21 (11.4 and 10.7 log(10) copy number g(-1) caecal content of the total bacteria and the Bacteroides-Prevotella group, respectively). The archaeal population could be detected only from day 7 onwards (5.5 log(10) copy number g(-1) full caecum) and reached its maximum level at day 35 (7.4 log(10) copy number g(-1) caecal content). Similarity analysis, diversity calculation and quantitative evaluation of the stability of bacterial community CE-SSCP profiles provided some evidence that the caecal microbiota develops progressively from a simple and unstable community after birth into a complex and climax community in subadult rabbits. Meanwhile, the microbial activity evolved with the progressive decrease of the propionate/butyrate ratio towards a rabbit-specific value <1.