Hard faeces reingestion and the passage and recycling of large food particles in the Japanese hare (Lepus brachyurus)

Abstract

Upon finding the regular reingestion of hard faeces, we studied the passage and recycling of large particles in the diet of the Japanese hare (Lepus brachyurus) in relation to the timing of ingestion. Small, thin pieces of synthetic rubber, simulating large food particles, were mixed with commercial food pellets and subjected to voluntary intake during a short period of time at night, and their subsequent excretion in the faeces was recorded. Irrespective of time at intake, the markers were almost completely excreted by the end of the second night: when ingested early in the evening, most were excreted within that night, and as ingested later on, they were increasingly excreted on the second night. All hard and soft faeces excreted during the daytime resting period were reingested, and the markers, contained in both types of the daytime faeces, were thereby recycled. The results show that large particles in the diet are given another chance for digestion, through remastication and reingestion, when they are excreted during the daytime following ingestion. This suggests that hard-faeces reingestion does not result in multiple recycling of poorly digestible large particles and leading to inefficiency in digestion.Resume. -A l'occasion de recherches sur la reingestion des crottes dures, nous avons etudie le passage et le recyclage des grosses particules dans le regime alimentaire du lievre du Japon, Lepus brachyurus, en relation avec le moment de l'ingestion. De petits morceaux de caoutchouc synthetique, simulant de grosses particules alimentaires, ont ete melanges avec des granules de nourriture du commerce, soumis a une prise volontaire pendant une courte periode de la nuit, et on a enregistre l'heure de leur excretion dans les feces. Quelle que soit l'heure de leur absorption, les marqueurs etaient presque completement excretes a la fin de la seconde nuit: quand ils avaient ete ingeres tot dans la soiree, la plupart etaient excretes dans la nuit meme, et quand ils avaient ete ingeres plus tard, ils etaient excretes en plus grand nombre au cours de la seconde nuit. Toutes les crottes, dures ou molles, excretees pendant la periode de repos diurne, etaient reingerees et les marqueurs, contenus dans ces deux types de crottes, etaient de ce fait recycles. Les resultats montrent que les grosses particules contenues dans le bol alimentaire ont ainsi une seconde chance d'etre digerees, par l'intermediaire de la remastication et de la reingestion, quand elles sont excretees pendant la journee suivant leur ingestion. Ceci suggere que la reingestion des crottes dures n'a pas pour resultat un recyclage multiple des grosses particules difficiles ä digerer, induisant a une inefficacite de la digestion. Mammalia, t. 59,;/° 2, 1995 : 237-247.

Comparisons of digestive function between the European hare (Lepus europaeus) and the European rabbit (Oryctolagus cuniculus): Mastication, gut passage, and digestibility

“…The minimum passage time in these animals (2 h) matched the minimum passage time for synthetic rubber marker fragments recorded for the Japanese hare Lepus brachyurus (Hirakawa and Okada 1995). The records of MRT of particulate fibre in rabbits (e.g., 43.4 h, Sakaguchi et al 1992) and hares (e.g., 15.5 h, Kronfeld and Shkolnik 1996) are only valid if the tests are rigidly standardised because MRT is sensitive to the physical form of the fibre (Fraga et al 1991) and because of the potential for a chemical marker to influence FSG (Ehle 1984) and hence passage rate.…”

“…Jack Zhou, Corporate Product Characterisation, Ethicon Research and Development), whereas 21% of the composition of mature lucerne hay has a FSG in the range 0.90-1.30 g cm À3 , and 79% is o0.90 g cm À3 (Hooper and Welch 1985). Pickard and Stevens (1972) demonstrated that particles with two dimensions 42.0 mm are selectively retained in the stomach of the rabbit, and Bjo¨rnhag (1972) demonstrated that particles with a dimension o0.1 mm are selectively retained in the caecum of the rabbit, and fibres 1-2 mm in length are found in the normal faeces of a (Japanese) hare (Hirakawa and Okada 1995). Hence, 1.8 mm lengths of the 0.45 mm diameter polypropylene thread were used.…”

“…The passage times were calculated after Hirakawa and Okada (1995). Minimum passage time was the time from ingestion to the first appearance of the marker in the faeces.…”

Significance of Coprophagy for the Fatty Acid Profile in Body Tissues of Rabbits Fed Different Diets

“…This phenomenon could be explained by the digestive strategy of coprophagy of rodents and other small herbivores [9]. Coprophagy has been studied particularly well in rabbits [18,24,40,41]. Hirakawa [9] describes that wild rabbits recycle almost the entire undigested matter in the form of caecotrophs.…”

Comparative in vitro study of caecal microbial activity in brown hares and domestic rabbits which were offered the same diet

“…The reingestion of soft faeces provides additional protein, minerals and vitamins to the animal (Hirakawa 2001), but this mechanism is not identical in both rabbits and hares. Rabbits are better able to separate the fibrous fraction and to produce larger amounts of soft faeces as a cluster surrounded by a mucilaginous membrane than hares, which produce an amorphous type of soft faeces that lacks a membrane (Hirakawa and Okada 1995;Hirakawa 2001;Kuijper et al 2004).…”