The effect of some herbal extracts on nutrition and growth performance, digestive enzymes activity and immune parameters of rainbow trout (Oncorhynchus mykiss)

Abstract

The effects of Conocarpus erectus, Paulownia fortunei extracts and their mixture (50%+50%) on the growth performance, digestive enzymes activity and non-specific immunity of rainbow trout (Oncorhynchus mykiss) were studied. Fish were divided into 4 four experimental groups fed diets with 0% (T1), 1% of conocarpus extract (T2), 1% of paulownia extracts (T3) and their mixture (T4) for 30 days. One- hundred and eighty fish (57.00± 4.09 g) were randomly stocked in twelve 70-L Aquarium assigned into three treatments and a control group. The growth performance was significantly increased in all herbal extracts fed fish compared to the control (P < 0.05); the highest value was obtained by treatment 4. The food conversion ratio (FCR) was improved in all experimental treatments compared to control. The digestive enzymes levels revealed significant increment in fish fed 1% Paulownia extract (T3) in comparison with the other treatments and control. There were no significant difference in protein and albumin levels of fish blood serum in different experimental treatments and control (P > 0.05). While, glucose and hemoglobin levels were significantly increased in fish fed diets containing plant extract. The results of this experiment showed that the use of conocarpus and paulownia extracts can improve the growth, digestive enzymes and non-specific immunity of the O. mykiss.