Intestinal histology and stereology in rainbow trout (Oncorhynchus mykiss) administrated with nanochitosan/zeolite and chitosan/zeolite composites

Abstract

In previous study, the effects of synthesized chitosan/zeolite and nanochitosan/zeolite composites on rainbow trout growth, digestive enzyme activities and some biochemical parameters were shown. In this study, the effects of experimental diets based on the previous study on the rainbow trout intestinal histology and stereology were assessed: control diet (no zeolite and composite), T1 diet (14.28g/kg zeolite), T2 diet (0.05g/kg chitosan included in zeolite), T3 diet (0.5g/kg chitosan included in zeolite), T4 diet (5g/kg chitosan included in zeolite), T5 diet (0.05g/kg nanochitosan included in zeolite), T6 diet (0.5g/kg nanochitosan included in zeolite), T7 diet (5g/kg nanochitosan included in zeolite). The experiment was conducted for 60days. Results showed that supplemental diets did not have side effect on the normal structure of intestinal segments but administration of T1 and T4 diets had slight negative effects on structural maintenance in the middle part of intestine. Acidic mucin producing goblet cell percentage was also higher in nanocomposites-administrated groups in comparison with the control group. Enhanced villus height, density and finally absorption surface area in different parts of rainbow trout intestine were mainly shown in T7 group. Meanwhile, higher thickness of tunica mascularis in different regions were noted in treatment groups especially in T7 group. The number of intraepithelial mononuclear leukocytes in fish intestine received treatment diets was also higher than control group. In conclusion, nanochitosan/zeolite composites in comparison with zeolite and chitosan/zeolite composites were more effective to improve histological structure of rainbow trout intestine.