Descriptive Comparison of Gastrointestinal Tract Histology of Various Avian Species based on their Natural Diet

Abstract

Many animals species develop their gastrointestinal tube with special features to accommodate their natural diet to survive under adverse conditions including the nutrient absorption capability. Information related to the histologic description of various bird species' digestive organs based on their diet and its significance is yet limited. This study aimed to present a descriptive explanation of gastrointestinal organs of a changeable hawk-eagle (Nisaetus cirrhatu) and oriental honey buzzard (Pernis ptilorhynchus) as carnivorous, a southern cassowary (Casuarius casuarius) as an omnivorous, and a domestic chicken (Gallus gallus) as granivorous. In the current study, proventriculus (glandular stomach) and intestinal segments were microscopically examined and compared to understand the special histological features among avian species due to their important roles to digest the ingesta. The dissected specimens were preserved in 10% non-buffered formalin, then were processed through the common standard procedure of tissue processing and eventually stained with haematoxylin-eosin. Microscopic observation showed variation in shape and size of proventricular glandular architecture among raptors. The intestine muscular layer of the cassowary also showed distinct thickness among birds. These results of the study preliminary proved that variation in diet might affect the histologic features of avian gastrointestinal tracts.