Complement system activation in red tilapia (Oreochromis sp.) orally administered with probiotics SEAL

Abstract

The purposes of this study were to determine the effect of probiotic application on the non-specific humoral immune system in red tilapia infected with Aeromonas hydrophila in a laboratory and field trial. Yeast and bacterial strains of different origin (Sacharomyces sp., Enterobacter sp. JC10, Aeromonas sp. JC33, and Lactococcus sp. JAL12) were administered to fish in daily and three day intervals at a dose of 5x104 cfu/gram feed. Fish were infected with A. hydrophila in the LD70 dose on 23rd day of treatment. All parameters were examined at one and two months of probiotic application, and 7 days of pathogenic bacteria infection. The results showed that dietary probiotics enhanced and prolonged serum antibacterial activity and total plasma protein. All probiotic application intervals induced higher bactericidal complement activity than the controls. Data on total plasma protein also indicated an increased in the humoral factor of probiotics treated fish. In the case of A. hydrohila infection, only the daily treatment of probiotics was able to keep the complement bactericidal activity of higher than the control. Field application of the probiotics required the probiotic doses of at least 105 cfu/gram feed to obtained an improve complement bactericidal activity.