Fibre intake and faeces quality in leaf-eating primates

Abstract

A high incidence of gastrointestinal disorders as diarrhea, phytobezoars, bloated conditions and weight loss have been observed in captive langurs. This thesis focuses on the effect of the food intake in captive langurs in relation to the quality of faeces and its implications for langurs kept in captivity. According to the literature colobines have a compartmentalized stomach in which food is fermented. The structure and size of the hindgut suggests that fermentation also can take place there. Comparing the digestive tract of langurs with ruminants showed a lot of similarities. Results of a nutrition questionnaire sent to North American and European facilities showed that currently there is no standardized diet fed to Southeast Asian colobines kept in captivity. Chemical analyses of wild fruits, seeds and leaves showed high levels of NDF and indigestible fibre. Langurs prefer a diet containing carbohydrates which are easily digested, but when such a diet is not available, langurs consume diets with more fibre and less digestible carbohydrates. A study showed an improvement of stool quality when a high fiber pellet was fed to François langurs (Trachypithecus françoisi) Feeding a high fibre pellet resulted in less distinct feeding peaks and eating was distributed over the whole day in a group of François langurs Experiments with captive black and white colobus (Colobus guereza)and spectacled leaf monkeys (Trachypithecus obscurus) showed that faeces quality improved for these foregut fermenting primates when feeding more crude fiber and cellulose. In two groups of Javan langurs (Trachypithecus auratus auratus) in two facilities the effect of removal of produce from the diet was tested. Results in both facilities showed that the faeces quality improved when the diet consisted only of browse and a high fiber pellet. Exclusion of feeds rich in soluble carbohydrates in the diet of Javan langurs caused an increased intake of high fiber pellets and browse. This resulted in a higher fiber intake and a lower dietary water intake and an improvement of the faeces quality. Mean Retention Time (MRT) was calculated by analysing the amount of cobalt-EDTA and chromium oxide in the consumed food and produced faeces in Javan Langurs. No significant differences were found between the retention time of the fluid and particle part in two different diets. After feeding to Javan langurs a diet rich in alpha-linolenic acid instead of that rich in linoleic, a clear increase was shown in the content of alpha-linolenic acid in both plasma and erythrocytes. It indicates that dietary polyunsaturated fatty acids are hydrogenated in the stomach. Comparison of 11 diets fed in Dutch zoos showed that faeces consistency depends on dietary water, protein content and fibre content. High water and protein intakes were associated with deteriorated faeces consistency, where as high fibre intake was associated with improved faeces quality. In relation to the faeces quality, captive langur diets should have a higher dry matter and fibre content and a lower protein content when compared to free-ranging diets.