Observations on the macroscopic anatomy of the intestinal tract and its mesenteric folds in the pampas deer (Ozotoceros bezoarticus, Linnaeus 1758).

We described the macroscopic anatomy of the intestines and their peritoneal folds of five adult pampas deer (Ozotoceros bezoarticus), a cervid species considered to ingest a high proportion of grass in its natural diet. The mean (+/-SD) body weight was 17 (+/-2) kg. The small intestine and the caecocolon measured 495 (+/-37) cm and 237 (+/-24) cm in length, respectively, with an average ratio (small intestine:caecocolon) of 1.9 (+/-0.1). The ascending colon had two and a half centripetal gyri, a central flexure and two centrifugal gyri. The spiral ansa, which was similar to an ellipse, was fixed to the whole left face of the mesenterium. Apart from the peritoneal folds described in the Nomina Anatomica Veterinaria, three additional, hitherto not described folds were found: a fold that fixed the caecum to the proximal ansa of the ascending colon, one that joined the terminal part of the proximal ansa to the last centrifugal gyrus of the spiral ansa of the ascending colon, and one that linked the ascending duodenum to the proximal ansa of the ascending colon. When compared with published data from other cervids of different feeding niches, it appears that, among cervids, the ratio of small intestine to the caecocolon length does not reflect the natural diet.