Fibre digestion and digesta retention time in guinea-pigs (Cavia porcellus), degus (Octodon degus) and leaf-eared mice (Phyllotis darwini).

1. Digestibilities of feed and turnover time (1/k), Transit time (TT) and mean retention time (MRT: 1/k + TT) of fluid and particle markers were measured in the guinea-pig (Cavia porcellus), degu (Octodon degus) and leaf-eared mouse (Phyllotis darwini) fed a diet containing 50% alfalfa. 2. The digestibility of fibre and the retention time of digesta were highest in the guinea-pig followed by the degu and lowest in the leaf-eared mouse. 3. The difference in the retention time of digesta, resulting from the variation in the digestibility of fibre, between the three animals can be considered to be related to their body mass.