MORPHOPHYISOLOGICAL SPECIALIZATION AND ADAPTATION OF THE MOOSE DIGESTIVE SYSTEM

Abstract

During comparative studies of 66 ruminant species considering feeding habits and multiple morphological criteria along the digestive tract, moose specimens from one Swedish and two Finnish populations were studied. Data were evaluated relative to body mass. Focal points of specialisation in the head section where salivary glands, tongue and palate; Furthermore all forestomach portions with the comp. small proximal fermentation chamber (PFC) and the large intestine with its relatively large distal fermentation chamber (DFC). Total salivary gland weight is changing from c.0.18 (winter) to 0.14 - 0.18 (summer). The mobile free end of the tongue is at 36% above feeding type average, combined with a short torus linguae. Ruminoreticular capacity (411, range 30-721) is utilized at only 50-55%, omaso-abomasal capacity is 1:9 - 1:11 to ruminoreticular capacity. Rumen mucosa is evenly papillated but its surface regionally and seasonally differently enlarged, Pilae ruminis comparatively weak. Omasum extreme small, offers merely 1/5 of the absorptive surface of sheep or 1/3 of red deer omasum. All stomach ostia are comp. wide facilitating rapid food passage. Absomasal fundic mucosa is almost 100% thicker than average mucosal thickness of 14 grazing ruminant species. DFC volume is at 10-12% of PFC volume typical for concentrate selectors, unusual is the ratio of small to large intestine length (60-76 : 40-45%). The spiral colon is almost 30% of total intestinal length. Moose are seasonally adaptable concentrate (foliage) selectors depending on forage plant diversity.