Limitation of body mass of herbivores

Abstract

That the length of digesta passage rate of large herbivores was influenced by the BM of the animal was discussed controversial in the past and recently. However, recent studies with increasing data sets show tendencies to very low or not existent influences of animal BM on mean retention times. The results of this study contribute the findings that there is no significant relation between these two factors.<br /> Digestibility trials comparing ruminants and hindgut fermenters show higher fibre digestibilities in ruminants than in hindgut fermenters. But digestibility trials were time and labour-intensive and impossible to conduct for some wild animal species. This study tried to show differences between these groups by using an in vitro test. It was possible to show higher fibre digestibilities in ruminants by using the Hohenheim-gas-test by using the faecal fibre residues of the animals. <br /> Studies showed that it is possible to get information about the ingested food quality by analysing the faecal nitrogen of the animals. With samples of free ranging wild herbivores (Northern Kenya) this study tried to draw conclusions about the relation between body mass and food quality. In previous studies tannins, which were included in browse, disturb the analysis and negatively influence the expressiveness of the results. Hence in this study a modified faecal nitrogen analysis was used, and it was possible to show a decrease in food quality/selectivity with increasing BM for ruminants by using the metabolic faecal nitrogen data. Using the total faecal nitrogen data, no relation could be calculated. For the hindgut fermenters a trend of decreasing food quality was found. This might be based on the season in which the samples were collected. This fact should be controlled for in a future study which was conducted during or at the end of the rainy season.