Gross and histological studies of digestive tract of broilers during postnatal growth and development

Abstract

We studied anatomy and histology of different segments of the digestive tract in postnatal growing broiler chickens  with regard to their location, shape, size and weight. A group of four chickens, each at day 1 (D1), days 14 (D14) and  days 28 (D28), total 12, were killed, their digestive tracts were dissected and described and shape, size and weight of  different segments were recorded. Samples from different segments were prepared and stained with haematoxylin  and eosin staining technique to study the histology under light microscope. The average lengths (cm) and weights  (gm) of esophagus, proventriculus (glandular stomach), gizzard (muscular stomach), small intestine and large  intestine were significantly higher (P<0.01) in chickens at D28 than that at D14 and at D1. The histological layers of  digestive tract were lamina epithelia, lamina propria, lamina muscularis, submucosa, tunica muscularis and serosa  with the exception in esophagus where outer adventitia was found. The esophageal glands were significantly more in  numbers at D1 (in cross section, 12 in number per focus under 100x) than at D14 (6 in number per focus under 100x)  and at D28 (2 in number per focus under 100x). The proventriculus consisted of macroscopic papillae with numerous  microscopic folds with lamina propria comprised of simple glands, which converged into a common cavity near the  surface. In gizzard, the cuticle, in the form of wavy lines ran parallel to the surface. The villi of small intestine and  large intestine were lined by simple columnar epithelium. The apical parts of villi of the duodenum were slightly  pointed and the basal parts of the villi were thicker than jejunum and ileum, whereas, the villi of the jejunum and ileum  became shorter and broader than duodenum and most of the villi had blunt apical part and the basal parts were  wider. The numbers of goblet cells were numerous in number in ileum than duodenum and jejunum. Plicae ran along  the inner surface of the distal two thirds of the cacea. However, in the colorectum, the villi appeared as numerous  long flat leaf-shaped structures which filled a large proportion of the lumen. The average lengths and widths of villi of  small and large intestine were significantly higher (P<0.01) in chickens at D28 than that at D14 and at D1. The number  of goblet cells in lamina epithelium and intestinal glands of the lamina propria were numerous in number at D28 than  the chickens at D14 and at D1.   DOI: http://dx.doi.org/10.3329/jbau.v10i1.12096   J. Bangladesh Agril. Univ. 10(1): 69–77, 2012