EFFECTS OF DIETARY WALNUT LEAF EXTRACTS ON GROWTH PERFORMANCE, HEMATOLOGICAL PARAMETERS, AND DISEASE RESISTANCE IN RAINBOW TROUT, Onchorynchus mykiss

Abstract The present study investigated the effects of dietary ethanolic extracts of walnut leaves (Juglans regia) on growth performance, hematological parameters and disease resistance of Rainbow trout (Oncorhynchus mykiss) against Aeromonas salmonicida. Five isonitrogenous and isoenergetic diets were prepared to contain walnut leaf ethanolic extract at rates of 0, 750, 1000, 1500 and 2500 mg/kg diet. Fish were fed with experimental diets for 21 days. Growth performance and hematological parameters were found to be similar in all experimental groups. The dietary incorporation of ethanolic extract of walnut leaf significantly improved disease resistance against Aeromonas salmonicida. In conclusion, findings of the present study indicate that walnut leaf ethanolic extract might be a promising substitute for antibiotic additives against Aeromonas salmonicida pathogen in rainbow trout feeds