Food generally passes through a rabbit twice, A Blog Around the Clock reminds you, and provides citations to several studies that, should you read them, will expand your knowledge of the phenomenon:
[R]abbits are small. They have a single small stomach, and as much intestines as they can pack into their small bodies, and as large a cecum as they can get. But that is not enough – the food, half digested, passes through them too fast…. Food goes through the rabbit twice. Not once, not three or four times, just twice…. The droppings that passed through the rabbit only once – caecotrophs – are small and soft and clumped up like grapes. They are apparently yummy to rabbits and get eaten. Droppings that made the passage through the rabbit twice are larger, separate from each other, and dry….
1. Bellier R, Gidenne T, Vernay M, & Colin M (1995). In vivo study of circadian variations of the cecal fermentation pattern in postweaned and adult rabbits. Journal of animal science, 73 (1), 128-35 PMID: 7601725
2. Kenagy, G., & Hoyt, D. (1979). Reingestion of feces in rodents and its daily rhythmicity Oecologia, 44 (3), 403-409 DOI: 10.1007/BF00545245
3. Kenagy GJ, Veloso C, & Bozinovic F (1999). Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy. Physiological and biochemical zoology : PBZ, 72 (1), 78-86 PMID: 9882606
4. Hörnicke H, Ruoff G, Vogt B, Clauss W, & Ehrlein HJ (1984). Phase relationship of the circadian rhythms of feed intake, caecal motility and production of soft and hard faeces in domestic rabbits. Laboratory animals, 18 (2), 169-72 PMID: 6748594
5. Pairet M, Bouyssou T, & Ruckebusch Y (1986). Colonic formation of soft feces in rabbits: a role for endogenous prostaglandins. The American journal of physiology, 250 (3 Pt 1) PMID: 3456721