Digestive physiology and hindgut bacterial community of the young rabbit (Oryctolagus cuniculus): effects of age and short-term intake limitation.

The digestive response of the young rabbit to a short-term (28-53 days) limitation of its voluntary intake (25%) was analysed according to age and in relation to the incidence of digestive troubles. Several physico-chemical parameters of the caecal biotope were studied in relation to the caecal bacterial community structure and diversity, and with other physiological criteria (stomach pH, ileum morphometry and maltase activity). The morphometry of the ileum was significantly affected by age (36 vs. 52 days) but not by the intake level, while the relative maltase activity remained unchanged. In the stomach, the pH of antrum and fundus increased by approximately 1/3 between 36 and 52 days, and was 31% (P=0.003) and 79% (P<0.001) higher for restricted compared to ad libitum rabbits respectively. However the caecal pH remained unchanged (mean: 5.83). The caecal redox potential increased slightly, by 8 units (P=0.02), when intake was limited, but did not change between 36 and 52 days. The caecal bacterial diversity increased with age (4.8 vs. 5.2, P=0.014) while bacterial structure was modified. Limiting the intake for 16 days did not modify the structure or the diversity of the bacterial community.