Both quantitative and energetic intake level affect caecal microbiota composition and activity in the growing rabbit

Abstract

International audienceShort-term feed restriction strategies reduce rabbit post-weaning digestive disorders, but little is known about the implications of the caecal ecosystem in these beneficial effects. Our study looks into the consequences of feed (quantitative) and energy intake level on the caecal ecosystem. At weaning 320 rabbits were allotted into four groups: HE100, HE75, LE100 and LE75, differing in dietary digestible energy concentrations (HE = 10.13 vs LE = 9.08 MJ DE/kg, calculated values) and intake levels (100 = ad libitum vs 75 = restricted at 75% of ad libitum). Caecal content was sampled in ten rabbits per group at 42 and 50 days of age for ammonia and volatile fatty acid concentration measurements and for bacterial composition determination using 16S DNA sequencing. Restricted feed intake increased the acetate proportion (+2.8 units, P<0.001) and decreased that of butyrate (-2.4 units, P<0.001), while high energeticintake (HE diet) mainly decreased the caecal pH (-0.14, P<0.001). Akkermansiaceae were increased with high energeticintake (0.54 vs 0.25%, p adjust <0.05), while Christensenellaceae were decreased (2.8 vs 5.6%, p adjust <0.001) and Eubacteriaceae increased with restricted feed intake (10.5 vs 6.9%, p adjust <0.05). Altogether, our results indicated that quantitative and energeticintake level modified the caecal microbial activity and composition. These modifications deserve further investigation to determine the potential causal link between microbial composition, activity and impacts on the host's health