Effect of kelp Ascophyllum nodosum supplement in diet on resistance to disease in black tiger shrimp Penaeus monodon

Abstract

Effect of kelp Ascophyllum nodosum supplemented diets on Penaeus monodon was tested in two experiments. All experiments were used diets consisted of 40% protein and 10% fat. A. nodosum meal was mixed to shrimp basal diet at concentration of 0, 2.5, 5, 7.5 and 10%. In experimental 1, a 28 days feeding trail was conducted on postlarvae-15. The experiment was tested in cages installed in a closed recirculting water system. At the end of the experiment, shrimp's growth data showed that shrimp fed 2.5% kelp added diet had the highest average length, but was not significantly different from the other diets. Survival rate of shrimp fed 2.5% kelp diet was significant higher than those shrimp fed other diets. In experimental 2, shrimp at the age of 1.5 month-old was tested with the same previous diets for 56 days in cages that were installed in a earthen pond. The resulted showed that the length of shrimp fed different diets were no significant difference. However, when the weight was considered shrimp fed 5% of kelp supplement had significant higher weight (8.00+-2.32 g) than those shrimp fed 2.5, 7.5 and 10% kelp added, but not the control one (7.53+-2.60, 7.23+-2.40, 7.40+-2.43 and 7.62+-2.74 g, respectively). Shrimp production per cage showed no significant difference amount the diets. Survival rate of shrimp fed 2.5% was significantly higher than those of shrimp fed other diets. In disease resistant test with Vibrio harveyi, shrimp fed all the diets did not show any significance in total hemocyte count and phenoloxidase activity. The survival rate and LD[subscript 50] of the shrimp after challenging test indicated that shrimp fed 2.5% kelp added diet was significantly higher than those shrimp fed other diets.