In comparison to untreated control fish, respiratory
burst activity of blood cells was raised significantly in the LAB4 treated group on week 2. Serum-mediated killing of
Escherichia coli was increased significantly in group LAB6 on week 2. Serum immunoglobulin levels were significantly
raised only in LAB8 group on week 1 and in LAB4 and LAB8 at the end of the trial.