Differences in the range of faecal dry matter content between feeding types of captive wild ruminants

The dry matter content of 245 faecal samples of 81 species of captive wild ruminants was investigated. Samples were taken from 10 different zoos from temperate climate during the winter months. All animals had ad libitum access to drinking water. Species were classified as frugivores (FR, n = 5), browsers (BR, n = 16), intermediate feeders (IM, n = 35), and grazers (GR, n = 25). While no difference was observed in the average faecal dry matter content between the feeding types, the range of dry matter contents increased continually from FR, BR, IM to GR, ie both the driest and the wettest faeces of this study were produced by grazing ruminants. As it has been shown that faecal dry matter content is a function of the length of the colon descendens of a ruminant species, these results can be interpreted as an indication of a relatively limited variation in anatomical design in this respect in the evolutionary older FR and BR, and a relatively larger variation in anatomical design - and probably niche adaptation - in IM and GR. This corresponds to the greater range of habitat niches that IM and ÔR manage to occupy. Due to this increased variation in the anatomical design of the lower hindgut, GR are regarded as "morphophysiologically progressive rumi­nants", in contrast to BR which are regarded as "morphophysiologically conservative ruminants".