Histological Assessment of the Glandular Stomach in Cockatiels (Nymphicus hollandicus) Fed Different Dietary Regimens

Abstract

The purpose of the present study was to evaluate the effects of different dietary regimens on potential histological alterations of proventricular tissue in the adult cockatiel (Nymphicus hollandicus). Eighteen clinically healthy birds (6-8 months old) with body weights between 70-100 g were randomly divided into three groups (n=6). Group 1 (G1) was fed fruits and vegetables, Group 2 (G2) was fed abalanced diet (grains, fruits and vegetables) and Group 3 (G3) was fed sunflower seeds only. The animals were kept for two months under controlled environmental conditions (24-28 °C; 10-12 h light/day) with free access to feed and water. All birds were clinically healthy throughout the experimental period, and no mortality or abnormal behavior was recorded.

   The birds were euthanized and placed in dorsal recumbency and the proventriculus was carefully excised, fixed in 10% neutral buffered formalin and processed for histological examination using standard techniques.Then, tissue sections were stained with Harris hematoxylin and eosin (H&E) and Periodic Acid–Schiff (PAS) stain also Masson’s trichrome stain. The most important observations indicated a structural difference in the proventriculus among the groups, depending on the composition of the diet, with the fruits and vegetables group presenting a relatively thin muscle layer, small glandular diameter and fine septa between glands. In the balanced diet group, moderate development of the muscularis externa, diameter of the glands as well as thickness of the septa was observed, while in the sunflower seed group, increased thickness of the muscularis externa, enlarged glandular structures and widened septa were recorded. The morphometric measurements supported these findings, with significant differences in proventricular gland diameter and septal thickness between these groups. In conclusion, the findings suggest that the dietary composition is the main element affecting the metabolic activity and the structural integrity of the visceral organs, and is associated with visible structural variation in the proventriculus as a glandular stomach. Furthermore, these findings emphasize the significance of balanced nutrition for the normal physiological status and suggest that unbalanced diets may predispose birds to structural and functional modifications.