The Effect of Adding Aloe Vera (Aloe barbadensis) in the Diet on Growth Performance and Some Blood Parameters and Serum Biochemical Indices in Rainbow Trout (Oncorhynchus mykiss) Challenged with Saprolegnia parasitica

In this study, effects of aloe vera on growth performance, Hematology and serum biochemical indices and the resistance to Saprolegnia parasitica were studied in rainbow trout for 8 weeks. Aloe vera powder at levels of 0, 5, 10 and 15 g/kg were added to a basal diet. At the end of trial period, the fish were exposed to the fungus S. parasitica. The results showed that all treatments fed with aloe vera-included diets showed significant increases in weight gain, specific growth rate and reduced feed efficiency compared to the control. Also fish treated with aloe vera showed significant increases in hematology and serum parameters in comparison with control. However, significant reduction in mortality was observed in the treated fish with 15 g/kg diet of aloe vera compared to the other treatments and the control following challenging with S. parasitica, but 5 g/kg diet of aloe vera survival rate increased significantly compared with control. According to the results, the use of aloe vera powder, especially at a level of 5 g/kg in rainbow trout diet is recommended in order to improve growth and immunity parameters as well as boosting fish resistance against S. parasitica contamination.