Eff ect of diff erent levels of milkweed (Calotropis persica) seed powder on the growth parameters, immunity and gut microbiota of Oncorhynchus mykiss

An 8-week feeding experiment was conducted to investigate the inclusion potential of fi ve levels of Calotropis persica seed powder (CSP) (0, 10, 20, 30, 40 and 50 g/ kg of the basal diet) in rainbow trout (Oncorhynchus mykiss) diet, in a completely randomized design. To perform the test, 3600 fries (11.5 ± 3.64 g) were treated for 56 days. According to the results, the increase in milkweed seed powder up to 40 g/ kg, resulted in a signifi cant increase in specifi c growth rate and intestinal lactic acid bacteria count compared to the control (p < 0.05). Th e best results of survival rate, feed conversion ratio, hepatosomatic and gastrosomatic indices were achieved in the treatments receiving 20, 30, 40, and 50 g/kg CSP (p < 0.05). Antibacterial activity of skin mucus, lysozyme and alkaline phosphatase showed the highest level in the 40 g/ kg treatment (p < 0.05). Based on the results, the inclusion of 40 g/kg milkweed seed powder caused positive health eff ects and could be a suitable herbal feed additive in the rainbow trout diet.