Physical characteristics of rumen contents in two small ruminants of different feeding type, the mouflon (Ovis ammon musimon) and the roe deer (Capreolus capreolus)

Abstract

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...

Rumen physiology constrains diet niche: linking digestive physiology and food selection across wild ruminant species

“…The rumen contents of moose-type species are 55 homogeneous, whereas in cattle-type species they are separated into a dorsal gas dome 56 overlaying a fibrous raft, a fluid layer below, and 'sludge' formed by very dense particles in 57 the most ventral strata (Hofmann 1973). Differences in stratification between species have 58 been demonstrated based on investigations on passage kinetics of fluids and particles in the 59 reticulorumen (Hummel et al 2005;Clauss et al 2006b;Lechner et al 2010), physical 60 characteristics of rumen contents (Clauss et al 2009a;Clauss et al 2009b;Hummel et al 61 2009), or by ultrasonographic investigations (Tschuor and Clauss 2008). Several anatomical 62 features appear to reflect differences in stratification across species, notably the papillation 63 pattern of the rumen wall.…”

“…All animals had been shot during routine hunting 120 programs of Free State Nature Conservation in 2007. Rumen contents were sampled 121 following protocols applied in the previous studies (Clauss et al 2009a;2009b). 122…”

“…A convenient explanation 338 for this pattern is that animals that rely on browse material only must cope with a very high 339 load of secondary plant compounds -which necessitate, apart from avoidance via selective 340 feeding (Cooper and Owen-Smith 1985), salivary proteins that neutralize some of these 341 compounds (Robbins et al 1995;Fickel et al 1998). These proteins might explain the 342 observed greater rumen fluid viscosity observed in these ruminants (Robbins et al 1995;343 Jones et al 2001;Clauss et al 2009a;Clauss et al 2009b;Lechner et al 2010), and the 344 necessity for their production may be a reason for the larger salivary glands in 'moose-type' 345 ruminants (Hofmann et al 2008). However, this size difference may still not be large enough 346 to allow 'moose-type' ruminants a greater saliva fluid production, which might represent a 347 compromising effect due to the concomitant dilution of salivary proteins (Hofmann et al 348 2008).…”

Old World Ruminant Morphophysiology, Life History, and Fossil Record: Exploring Key Innovations of a Diversification Sequence

“…This depends on a density gradient of particles on the one hand (Baumont & Deswysen 1991, Lechner-Doll et al 1991, and on the presence of a fluid environment in the reticulum on the other, in which density-based sorting by flotation and sedimentation can occur. Therefore, the reticulum contents are always particularly moist in ruminants (Clauss et al 2009b(Clauss et al , 2009c. When digesta is passed from the reticulum to the lower digestive tract, this digesta therefore will contain a high moisture content, which constitutes a dilution factor that will require a high secretion output in the subsequent stomach and intestinal regions.…”

“…One of the major functions of the omasum as it is understood today is the absorption of fluid from the digesta that leave the reticulum (reviewed in Clauss et al 2006). Correspondingly, the digesta in the omasum are invariably much drier than in the reticulum (Clauss et al 2009b(Clauss et al , 2009c and also than in the subsequent glandular stomach, where acid and enzyme secretions increase the moisture content again. Notably, this fluid-reabsorption function should not be linked to a putative adaptation to dry environments; actually, those ruminant species with the largest omasum (cattle relatives; Clauss et al 2006) are the ones that have the highest fluid loss in their faeces and thus defecate in 'pies' (Clauss et al 2003(Clauss et al , 2004.…”