Hatt, J M (2009). Physical characteristics of rumen contents in two small ruminants of different feeding type, the mouflon (Ovis ammon musimon) and the roe deer (Capreolus capreolus). Zoology,. Postprint available at: http://www.zora.uzh.ch Posted at the Zurich Open Repository and Archive, University of Zurich. http://www.zora.uzh.ch Originally published at: Zoology 2009, 112(3):195-205. Physical characteristics of rumen contents in two small ruminants of different feeding type, the mouflon (Ovis ammon musimon) and the roe deer (Capreolus capreolus) AbstractIn domestic ruminants, the stratification of forestomach contents -the results of flotation and sedimentation processes -is an important prerequisite for the selective particle retention in this organ. A series of anatomical and physiological measurements suggests that the degree of this stratification varies between browsing and grazing wild ruminants. We investigated the forestomach contents of free-ranging mouflon and roe deer shot during regular hunting procedures. There was no difference between the species in the degree by which forestomach ingesta separated according to size due to buoyancy characteristics in vitro. However, forestomach fluid of roe deer was more viscous than that of mouflon, and no difference in moisture content was evident between the dorsal and the ventral rumen in roe deer, in contrast to mouflon. Hence, the forestomach milieu in roe deer appears less favourable for gas or particle separation due to buoyancy characteristics. These findings are in accord with notable differences in forestomach papillation between the species. In roe deer, particle separation is most likely restricted to the reticulum, whereas in mouflon, the whole rumen may pre-sort particles to a higher degree. The results suggest that differences in forestomach physiology may occur across ruminant species. In domestic ruminants, the stratification of forestomach contents -the results of flotation and 24 sedimentation processes -is an important prerequisite for the selective particle retention in 25 this organ. A series of anatomical and physiological measurements suggests that the degree of 26 this stratification varies between browsing and grazing wild ruminants. We investigated the 27 forestomach contents of free-ranging mouflon and roe deer shot during regular hunting 28procedures. There was no difference between the species in the degree by which forestomach 29 ingesta separated according to size due to buoyancy characteristics in vitro. However, 30 forestomach fluid of roe deer was more viscous than that of mouflon, and no difference in 31 moisture content was evident between the dorsal and the ventral rumen in roe deer, in contrast 32 to mouflon. Hence, the forestomach milieu in roe deer appears less favourable for gas or 33 particle separation due to buoyancy characteristics. These findings are in accord with notable 34 differences in forestomach papillation between the species. In roe deer, particle separation is 35 most likely restricted to the reticu...