Effect of dietary supplementation with rosemary (Rosmarinus officinalis ) and thyme ( Zataria multiflora) powders on intestinal histopathology of common carp (Cyprinus carpio ) fingerlings fed Roundup® contaminated diet

The present study was aimed to determine the intestinal histopathological changes of common carp fingerling following dietary exposure to Roundup® and the efficacy of dietary inclusion of medicinal plants thyme and rosemary powders to decrease such tissue changes. For this purpose, 300 fingerlings with an average body weight of 15±1.5g were randomly distributed to 5 treatments and fed at 3 different stages as follow: stage 1 with a diet containing 20g/kg of plant powder alone or in combination (treatments 3-5), stage 2 with a diet containing 2.3 mg/kg of Roundup® (treatments 2-5) and stage 3 feeding with diets with neither contaminant nor the medicinal plant powders. Results showed that at the end of the first stage, intestinal tissue had normal microscopic appearance. Pathological changes including necrosis, detachment of intestinal villus, vacuolation in intestinal epithelial cells, infiltration of inflammatory cells along with edema and hyperemia were observed at the end of the second stage in those groups exposed to dietary Roundup® (treatment 2), but those fish previously received diets supplemented with rosemary or thyme (treatments 3 and 4) showed mild tissue changes. Furthermore, simultaneous dietary administration of rosemary and thyme powders (treatment 5) resulted in better tissue protection. Based on the results of the stage 3, after two weeks long recovery period, tissue significant structure amendment was observed in comparison to the previous stage (P<0.05). In conclusion, dietary inclusion of medicinal plant Rosmarinus officinalis and Zataria multiflora powders could reduce the histopathological changes in intestine of common carp fingerling exposed to dietary Roundup®.