THE GASTROINTESTINAL-TRACT OF THE ROCK HYRAX (PROVACIA-HABESSINICA) .2. FLUID-FLOW, PRODUCTION OF SHORT-CHAIN FATTY-ACIDS AND ABSORPTION OFWATER AND ELECTROLYTES

In the digestive tract of the rock hyrax (Procavia habessinica), water is absorbed from the small intestine and from the wider part of the c onnecting colon running between the caecum and the colonic sac. Only l ittle water absorption occurs from these two fermenting chambers. The outflow from the caecum is much higher than from the colonic sac mainl y due to the effective absorption in the connecting colon with its ver y large absorptive area. A significant lower osmolality was found in t he caecal contents compared with the contents in the colonic sac. The Na/K ratio was 10.7 and 1.7, respectively in these sections. Short cha in fatty acids are produced at a rate of nearly 10 mmol/100 ml/hr in t he contents of both the caecum and the colonic sac. The results are di scussed in relation to the findings in domestic and laboratory animals .