Retention of solute and particle markers in the digestive tract of chinchillas (Chinchilla laniger).

The chinchilla (Chinchilla laniger) is a herbivorous hystricomorph South American rodent for which no mean digesta retention times have been reported so far. Six animals (mean body mass ± standard deviation: 513 ± 99 g) on a diet of grass hay and lucerne-based pellets were given a pulse dose of a solute (cobalt-EDTA) and a particle (chromium-mordanted fibre, <2 mm) marker with subsequent frequent faecal collection. Dry matter intake was 45.2 ± 8.0 g/kg(0.75) /day. Mean retention times were 22.2 ± 5.3 h for solutes and 25.4 ± 5.2 h for particles, with the difference being not significant within individuals. This indicates the presence of a 'mucus-trap' colonic separation mechanism, which is in accord with morphological descriptions of the typical colonic furrow in chinchillas. Corresponding to a strategy of colonic digesta separation and caecotroph formation, secondary marker excretion peaks indicated coprophagic events that were spaced approximately 12 h apart. Given that these retention times appear longer than measures reported for rabbits (Oryctolagus cuniculus) or guinea pigs (Cavia procellus), it would be interesting to compare the digestive efficiency of chinchillas on high levels of dietary fibre to other species.