title: Gross Measurements of the Digestive Tract and Visceral Organs of Addax Antelope (Addax nasomaculatus) Following a Concentrate or Forage Feeding Regime.
abstract: Differences in macroscopic measurements of the gastrointestinal tract have been hypothesized to correlate with the browser-grazer continuum in the natural diet of ruminants. However, to what extent these characteristics represent species-specific traits, or respond to the actually ingested diet, remains to be investigated. Twelve surplus addax antelope (Addax nasomaculatus) were divided into two groups and fed, for 3 months, either their usual diet, consisting of a concentrate feed with a limited amount of hay, or a diet of unlimited hay only. After culling, macroscopic measurements were compared between groups. The macroscopic anatomy of the addax showed many characteristics considered typical for grazing or 'cattle-type' ruminants. While both diet groups had mesenteric, pericardial and perirenal adipose tissue, these depots were subjectively more pronounced in concentrate-fed animals. Hay-fed animals had significantly heavier filled forestomach compartments, with corresponding significantly longer linear measurements. Masseter muscles and the surface of first-order omasal leaves were significantly more prominent in hay-fed animals, reflecting possible adaptations to overcome resistance of grass forage and to reabsorb fluid from increased rumination, but differences were not as distinct as reported between 'cattle-type' and 'moose-type' ruminants. Some measurements such as reticular crests and empty foregut mass remained stable between groups, indicating possibly genetically pre-defined characteristics less prone to change in adult life. The results emphasize the adaptability of ruminant digestive tract anatomy in adult animals even after a short period of time, but also suggest limits to this adaptability that reveals a species-specific anatomy regardless of the diet actually consumed.
authors.affiliation: Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.
authors.forename: S A
authors.initials: SA
authors.lastname: Tahas
authors.affiliation: Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Martin Jurado
authors.affiliation: Al Wabra Wildlife Preservation, P.O. Box 44069, Doha, Qatar.
authors.forename: S
authors.initials: S
authors.lastname: Hammer
authors.affiliation: Al Wabra Wildlife Preservation, P.O. Box 44069, Doha, Qatar.
authors.forename: A
authors.initials: A
authors.lastname: Arif
authors.affiliation: Institute of Veterinary Anatomy, Histology and Embryology, Veterinary Faculty, LMU Munich, Veterinärstr. 13, 80539, Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Reese
authors.affiliation: Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.
authors.forename: J-M
authors.initials: JM
authors.lastname: Hatt
authors.affiliation: Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Clauss
mesh_terms: D000018:Abomasum / Q000033:anatomy & histology; D000821:Animal Feed; D000818:Animals; D000866:Antelopes / Q000033:anatomy & histology*; D049628:Body Size; D004032:Diet; D005260:Female; D041981:Gastrointestinal Tract / Q000033:anatomy & histology*; D008297:Male; D009851:Omasum / Q000033:anatomy & histology; D006109:Poaceae; D012159:Reticulum / Q000033:anatomy & histology; D012417:Rumen / Q000033:anatomy & histology