College of Arts and Sciences

Effects of supplementation of dietswith freeze-dried Chaetoceros calcitrans to control Vibrio harveyi infection are
evaluated through immune responses, and disease resistance of juvenile Penaeus monodon. Total lipid and fatty
acid profile of Chaetoceros calcitrans is also analyzed. A challenge infection with 107 cfu/mL concentration of
Vibrio harveyi is intramuscularly injected to juvenile Penaeus monodon after 45 days of feeding of diets supplementedwith
15 g/kg and 30 g/kg dried Chaetoceros calcitrans. The use of dried Chaetoceros calcitrans is compared
with that of ß-1,3 glucan Curdlan, a commercial immune enhancer. Incorporation of 30 g/kg Chaetoceros
calcitrans in the diet enhances the immune system of shrimp as effected by high prophenoloxidase activity and
plasma protein concentration and is better compared to the commercially available Curdlan. Chaetoceros
calcitrans also contains polyunsaturated fatty acids (PUFAs) such as linolenic acid and eicosapentanoic acid
(EPA) which are responsible for its antibacterial action against Vibrio harveyi. All these biological activities of
Chaetoceros calcitrans add up to increase resistance of the juvenile Penaeus monodon to vibriosis as shown by
its high survival rate from the challenge infection with Vibrio harveyi. Therefore, it is worthwhile to use
Chaetoceros calcitrans as supplementary feed. Its effect in increasing the immune competence coupled with its
antibacterial action, make the shrimp resistant to luminous vibriosis that continues to affect the industry, thereby
augmenting aquaculture production.