Effect of different levels of milkweed (Calotropis persica)seed powder on the growth parameters, immunity and gut microbiota of Oncorhynchus mykiss

An 8week feeding experiment was conducted to investigate the inclusion potential of five 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 significant increase in specific growth rate and intestinal lactic acid bacteria count compared to the control (p amp;lt; 0.05). The 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 amp;lt; 0.05). Antibacterial activity of skin mucus, lysozyme and alkaline phosphatase showed the highest level in the 40 g/kg treatment (p amp;lt; 0.05). Based on the results, the inclusion of 40 g/kg milkweed seed powder caused positive health effects and could be a suitable herbal feed additive in the rainbow trout diet.