Protective effects of basil (Ocimum basilicum) ethanolic extract supplementation diets against experimentalAeromonas hydrophilainfection in common carp (Cyprinus carpio)

Abstract

This study evaluated the effects of basil (Ocimum basilicum) leaves extract supplement on growth, blood parameters and resistance to Aeromonas hydrophila in Cyprinus carpio fingerlings. Basil leaves were mixed thoroughly with feed at 0, 100, 200, 400, 800 and 1600 mg kg−1 of diet and were fed in triplicate group for 2 months. At the end of this period, growth performance and survival were determined. Then fish were challenged intraperitoneally with A. hydrophila and mortalities were recorded up to 10 days post challenge. Results indicated that WBC, RBC, Ht, Hb, total protein, albumin and globulin were higher (P < 0.05) in fish fed diets containing O. basilicum compared with the control. Highest specific growth rate values were observed in 400 mg kg−1 group. Feed conversion ratio was significantly lower (P < 0.05) in fingerlings fed 400 and 800 mg O. basilicum kg−1 dry diet. After 10 days post challenge, total protein, WBC, RBC and Hb were significantly higher in 400 mg kg−1 compared with other groups. These results reveal that a dietary O. basilicum leaves extract of 400 mg kg−1 fed for 60 days leads to increased growth performance and survival rate as well as improved feeding efficiency in common carp fingerlings rendering them more resistant against infection by A. hydrophila.