Feeding behaviour and caecotrophy in the young rabbit before weaning: An approach by analysing the digestive contents

Young rabbits consume milk, feed and soft faeces during the pre-weaning period, but the biological rhythm of intake were scarcely described. This work aimed to analyse the behaviour of ingestion and caecotrophy by analysing the stomach and rectal contents of young rabbits. Chronological samplings were performed according to a 4 × 3 factorial experimental design (17, 22, 28 and 35 days at 3, 8 and 23 h after suckling, respectively). Both digestive contents were examined and scored according to a discrete 4-step scale. Milk intake peaked around 22 days (26.6 g/rabbit) and decreased by 50% at 28 days. Stomach score for milk content showed a negative relationship with age. Dry feed intake reached 7.2 g/rabbit at 22 days, but was relatively variable among litters (CV = 44%). After 22 days, nutrient intake from the solid feed exceeded that of the milk. A higher pellet intake was observed during the night period (18:00-09:00 h) whatever the age. Dry feed in the stomach content was affected by age (17 versus 22, 28 and 35 days). From 22 days, milk and feed components were particularly distributed in the stomach: the coagulated milk was close to the wall of the fundus, whereas the feed was homogeneously spread. Soft faeces were not found until 28 days of age, and were located in the fundic region (25-30% of stomach profile). Stomach weight increased almost threefold from 17 to 35 days of age, but showed a slower development than the rest of the body from 22 to 35 days (relative stomach weight from 1.65 to 1.38%). High pH values (5.5-3.0) were found in the fundus at 3 and 8 hours after suckling. The pH in the antrum decreased from 4.19 to 1.90 at 17 and 22 days, respectively. The excretion of hard and soft faeces was indirectly recorded by checking the content of distal colon and rectum. From 22 days onwards, the amount of hard faeces in distal colon and rectum reached a peak at 8 h after suckling (2.3 ± 0.2). On the contrary, soft faeces were only observed at 3 and 23 h after suckling from 28 days of age.