Comparative omasum anatomy in ruminants: Relationships with natural diet, digestive physiology, and general considerations on allometric investigations
| Autor: | Reinhold R. Hofmann, Marcus Clauss, Jürgen Hummel, Christian Ehrlich, Daryl Codron |
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| Přispěvatelé: | University of Zurich, Clauss, Marcus |
| Rok vydání: | 2018 |
| Předmět: |
0106 biological sciences
0301 basic medicine 10253 Department of Small Animals Omasum feeding niche Ontogeny Zoology 010603 evolutionary biology 01 natural sciences Ruminantia 1309 Developmental Biology 03 medical and health sciences Ruminant Digestive System Physiological Phenomena Animals Body Size Least-Squares Analysis Phylogeny convergence 630 Agriculture biology Enzymatic digestion Body Weight rumination Ruminants “moose biology.organism_classification Digestive physiology “cattle Diet Gastrointestinal Tract Digesta washing 030104 developmental biology type” 570 Life sciences Animal Science and Zoology Digestive tract Animals Zoo Allometry 1103 Animal Science and Zoology Omasal laminae Developmental Biology |
| Zdroj: | Journal of morphology. 280(2) |
| ISSN: | 1097-4687 |
| Popis: | The omasum is the third forestomach compartment of pecoran ruminants. It is assumed that the re-absorption of fluid present in the forestomach digesta (that facilitates particle sorting, digestion, and harvest of microbes) is its main function, so that less diluted digesta is submitted to enzymatic digestion in the lower digestive tract. Here, we evaluate measures of omasum size (representing 84 ruminant species in the largest data set) against body mass and proxies of the natural diet (% grass) or forestomach physiology (fluid throughput), using phylogenetically controlled models. The origin of specimens (free-ranging or captive) did not have an effect in the data set. Models with the best support invariably either included %grass or a physiology proxy in addition to body mass. These effects were not necessarily additive (affecting the intercept of the allometric regression), but often indicated a change in the allometric body mass-exponent with diet or physiology. Only models that allowed an influence on the allometric exponent yielded basic exponents compatible with predictions derived from geometry. Species that include more grass in their natural diet, or that have a “cattle-type” physiology marked by a high forestomach fluid throughput, generally have larger omasa. However, the existence of outliers, as well as the overall data pattern, suggest that this is not an obligatory morphophysiological condition. Circumstantial evidence is presented leading to the hypothesis that the comparatively small and less complex omasa of “moose-type” species do not necessarily represent an “original” state, but may be derived from more complex states by ontogenetic reduction and fusion of omasal laminae. |
| Databáze: | OpenAIRE |
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