title: Dry matter and digesta particle size gradients along the goat digestive tract on grass and browse diets.
abstract: Physical properties of the digesta vary along the ruminant digestive tract. They also vary within the forestomach, leading to varying degrees of rumen contents stratification in 'moose-type' (browsing) and 'cattle-type' (intermediate and grazing) ruminants. We investigated the dry matter concentration (DM) and the mean digesta particle size (MPS) within the forestomach and along the digestive tract in 10 goats fed grass hay or dried browse after a standardized 12-h fast, euthanasia and freezing in the natural position. In all animals, irrespective of diet, DM showed a peak in the omasum and an increase from caecum via colon towards the faeces and a decrease in MPS between the reticulum and the omasum. Both patterns are typical for ruminants in general. In the forestomach, there was little systematic difference between more cranial and more caudal locations ('horizontal stratification'), with the possible exception of large particle segregation in the dorsal rumen blindsac on the grass diet. In contrast, the typical (vertical) contents stratification was evident for DM (with drier contents dorsally) and, to a lower degree, for MPS (with larger particles dorsally). Although evident in both groups, this stratification was more pronounced on the grass diet. The results support the interpretation that differences in rumen contents stratification between ruminants are mainly an effect of species-specific physiology, but can be enhanced due to the diet consumed.
authors.affiliation: Vetsuisse Faculty, Clinic for Zoo Animals, Exotic Pets and Wildlife, University of Zurich, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Clauss
authors.affiliation: Vetsuisse Faculty, Clinic for Zoo Animals, Exotic Pets and Wildlife, University of Zurich, Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Fritz
authors.affiliation: Vetsuisse Faculty, Department of Farm Animals, University of Zurich, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Tschuor
authors.affiliation: Vetsuisse Faculty, Department of Farm Animals, University of Zurich, Zurich, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Braun
authors.affiliation: Department of Animal Sciences, Ruminant Nutrition, University of Göttingen, Göttingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hummel
authors.affiliation: Florisbad Quaternary Research, National Museum, Bloemfontein, South Africa.|Centre for Environmental Management, University of the Free State, Bloemfontein, South Africa.
authors.forename: D
authors.initials: D
authors.lastname: Codron
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000502:physiology; D006041:Goats / Q000502:physiology*; D010316:Particle Size; D006109:Poaceae / Q000737:chemistry*
keywords: 
  Capra hircus
  ; browser; buoyancy; density; digestive physiology; fermentation; grazer