[Effects of beta-glucan on the growth, survival, and the efficacy of Anti-streptococcus iniae vaccine in rainbow trout [onchorhynchus mykiss]]

ABSTRACT

Glucans are complex polysaccharide components of yeast and fungal cell walls. This compounds can stimulate the fish immune system. The present study investigated the effects of Beta glucan[Macrogard] on growth, survival and some immunological parameters of rainbow trout [10 mg] and also on the efficiency of Streptococcus vaccine. Treatments of macrogard [1 g/kg food/day for 42 days], macrogard [macrogard 1 g/kg diet] with 15 minutes bathin vaccine, vaccine bath without macrogard and control were examined in a 42 daysperiod. In all treatments the fish growth [weight] showed a significant increase [p<0.05] compared to the control, while there was no significant difference among the treatments. The lyzosyme level of the blood serum showed a significant difference between control and the other treatments, the highest level was observed in the macrogaurd with vaccine treatment [2.7 micro g/ml] and the lowest level was observed in the control[0.5 micro g/ml]. Leukocytes count also had a significant difference between the control [3.3%Nuetrophil] and other treatments [6.6% Nuetrophil] [p<0.05]. The result of survival of fish challenged with Streptococcus iniae via bath route was 55%, while those for vaccine treatment, macrogard plus vaccine, macrogard every day and macrogard every 10 days interval were 75%, 86%, 60 and and 55%, respectively. The results of this study showed that supplement of macrogard has positive effect on growth and non-specific immune responses of rainbow trout and can enhance efficacy of anti-streptococcus iniae vaccine in this fish