Effect of Ascorbic acid supplementation on the resistance of Tilapia fish subjected to bacterial infection (Pseudomonas Fluorescens)

Abdelkader A. Abdulla

Faculty of Veterinary and Agricultural Science, Zawia University, Libya ??? ????? ??? ?????????? ??? ?????? ????? ?????? ??????? ?????? ????????? )?????? ?????????? ????????( ????????? ????????? ??????? ?? ????? ????? ??? ?????????? ??? ?????? ????? ?????? ?????? ????????? ??????? ?????????? ????????. ???? ??????? ????????? ????? ?????? ??????? ????? ????????? ? ?????? ???? ????? ???????????? )????? , 0555 ,055 ,005 ,005 ,05 ?????/????? ?????(??? ???? ????? ????? ??????? ??? ?????? ??????? ???? ???? ??? ??????? ???? ??????? ??? ???? ??????????? . ??? ??? ?? ???? ?? ????????? ??????? ????? ?? ????? ?? ??????? )?????? ?????????? ????????( ??? ??? ?? ???? ???? ???? ???? ?? ?????? ??????? ???? ???? ??? ??????? ???? ??????? ??? ??? ?????????? ???? ??? ??????? ??? ?????? ?????? ??? ?????????? ?? ?????? ??? 0555 ???. ??? ???? ?? ???? ???? ?? ????? ???????? ???????? ???? ???????? ??? ?????? ????? ??? ?????????? ?? ???????. ?? ?? ??????? ?????? ?? ??? ?????????? ?? ????? ??? ?? ????? ????? ??? ??????? ??? ?????? ?????????.

Abstract :

The experiment was conducted in this study to determine the effect of ascorbic acid level on the resistance of tilapia fish subjected to bacterial infection. Purified diets with six levels (0, 50, 150, 250, 500 and 1000 mg/kg) of supplemented L-ascorbic acid (AA) were pelleted and fed to tilapia fish (20g) for 12 weeks. Tilapia fish were fed purified diets containing AA ranging from 0 (free diet) to 1000mg/kg diet until the external signs of deficiency were seen in fish fed free diet. At the same time, resistance to bacterial infection (Pseudomonas Fluorescens) was assessed for fish from the various dietary treatments. Mortality rates of fish experimentally infected with Pseudomonas Fluorescens decreased with increasing the dietary AA doses, ranging from 90% for fish fed the AA free diet to 10% for fish fed 1000mg AA/kg diet. The haemotological parameters were improved and the pathological lesions of bacterial infection were minimized gradually with increasing the ascorbic acid concentration in the diets. It could be concluded that ascorbic acid has an important influence on tilapia disease mechanisms and enhance resistance of tilapia fish to pseudomonas infection. Key words: Ascorbic acid, Pseudomonas Fluorescens, Tilapia.