Study on the effect of herbal extracts on the prevention and treatment of disease caused by Streptococcus agalactiae in tilapia (Oreochromis sp.)

Abstract

This study was conducted to evaluate the effect of herbal extracts in methanol from bitterweed (Andrographis paniculata), lemon balm (Elsholtzia ciliata), perila (Perilla frutescens) and white elicta (Eclipta prostrata), these herbal extracts were mixed into feed for prevention and treatment of Streptococcus agalactiae infection in tilapia (Oreochromis sp.). This bacteria strain was isolated from the infected tilapia in Dong Thap (serotype III) and in Thua Thien-Hue province (serotype Ib) used in this study. Bitterweed (Andrographis paniculata), lemon balm (Elsholtzia ciliata), perila (Perilla frutescens) and white elicta (Eclipta prostrata) extracts were mixed separately into feed with doses of 156 mg bitterweed; 1,250 mg lemon balm; 2,500 mg perila and 2,500 mg white elicta per one kg feed. Fish were infected experimentally by intraperitoneal injection with 0.1 mL of 104 CFU/mL of S. agalactiae serotype III or serotype Ib. The studied results showed that the above herbal extracts proved the high prevention of S. agalactiae infection in tilapia, especially when increasing the feeding
rhythm twice per week. The extract of bitterweed, perila or white elicta can be considered as potential herbal extracst for the prevention and treatment of disease caused by S. agalactiae in tilapia.