Effects of using GaroVak immersion vaccine in rearing juvenile Asian sea bass (Lates calcarifer)

The aim of this study was to investigate the effects of GaroVak immersion vaccine against lactococcosis and streptococcosis disease in different weights on growth and feeding performance and some immunological responses and survival rate of Asian Sea bass (Lates calcarifer). Fish with an average weight of 5, 10 and 14 g in 300-liter polyethylene circular tanks in 6 treatments and 2 repetitions including vaccinated groups in low (5 g), medium (10 g) and high-weights (14 g) (ST, MT, LT) and control groups of each the weight without vaccination (SC, MC, LC) were examined. Feeding was done twice a day ad libitum for 8 weeks. The obtained results showed that GaroVak immersion vaccine has no significant effect on growth and feeding performance the vaccinated fish and the control fish (P>0.05). Regarding immunological responses, the amount of total protein and albumin was significantly higher in the low weight-treatment (ST) compared to the low-weight control group (SC), and no significant difference was observed in the medium-weight and the high-weight between the vaccinated treatments and the control group (P>0.05). Also, vaccination did not show a significant effect on antibody titer and lysozyme activity in any of the treatments (P>0.05). In addition, the survival rate at the end of the experiment did not show a significant difference between the vaccinated treatments and the control group (P> 0.05). However, the result of the bacterial challenge showed that mortality rate in the low-weight vaccinated group (ST) was lower than the medium-weight control group (MC) (P<0.05). According to the general results of this study, administration of GaroVak immersion vaccine against streptococcosis disease has been able to improve the survival rate after bacterial challenge in low-weight of Asian seabass (5 g).