The allocation of a ruminant feeding type to the okapi (Okapia johnstoni) on the basis of morphological parameters

As the anatomy of the digestive tract of the okapi (Okapia johnstoni) has not been described in relation to the ruminant feeding type classification to date, we here report anatomical measurements on a complete digestive tract of an okapi euthanised in captivity and measurements of its ingesta particle size and forestomach protozoa species, supplemented with other information on two okapi forestomachs and anatomical literature data. The digestive tract of the okapi is characterised by a comparatively small reticulorumen (wet contents 9.8 % of body weight) with weak rumen pillars (thickness 7–10 mm), a shallow reticular honeycomb structure (reticular crest height 1–2 mm) and a small omasum (curvature 28–33 cm); particularly long papillae unguiculiformes have been reported and were found in one forestomach investigated, but are not a consistent finding. The ratio of the length of the small vs. large intestine was low (1.3–1.8). The liver investigated was comparatively large (1.56 % of body weight). Faecal particle size investigated was large compared to other ruminant data. Forestomach protozoa were almost exclusively Entodinium species. All these parameters are in accord with a classification as a typical browser according to Hofmann (1989). However, the parotid glands investigated represented only 0.071 % of body weight, which is within the range typically reported for grazers. Potential causes and consequences of this finding are briefly discussed.