Relationships between aspects of the digestive physiology of herbivorous vertebrates.

<p>a) the relative food intake (per unit metabolic body weight) and the passage of digesta through the gastrointestinal trat (measured as mean retention time MRT or, in the case of some reptiles, as transit time TT) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068714#pone.0068714-Fritz4" target="_blank">[81]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068714#pone.0068714-Franz5" target="_blank">[112]</a>; note that species/individuals with a higher food intake have shorter retention times; note that flying birds show a similar relationship on a lower level, potentially due to their smaller gut capacity (cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068714#pone-0068714-g006" target="_blank">Fig. 6b</a>); b) body mass and foraging time for hindgut fermenters and ruminants <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068714#pone.0068714-OwenSmith1" target="_blank">[42]</a> (regression given for hindgut fermenters; extrapolation to 100% of the day yields an upper BM limit of app. 18 tons).