The present study demonstrates the effects of dietary freeze-dried Chaetoceros calcitrans supplementation on immune responses, antibacterial action, and resistance of juvenile Penaeus monodon against Vibrio harveyi infection.
Shrimps fed on control and experimental diets showed no significant difference in growth and survival before the challenge test. Neither did it show marked variation in feeding behavior and vigor. Thus, survival, growth, and vigor were not affected by dietary Chaetoceros calcitrans supplementation. But, following Vibrio harveyi challenge, supplementation level of freeze-dried Chaetoceros calcitrans had a significant effect on survival. Mortality of more than 50% was observed in all treatments except in the shrimp fed with 30 g/kg Chaetoceros calcitrans. The survival rate between the shrimp fed with 30 g/kg and that with Curdlan (positive control) showed no significant difference, but were significantly different compared to the shrimp fed with unsupplemented diet and 15 g/kg Chaetoceros calcitrans