Effect of a Dunaliella extract on growth performance, health condition, immune response and disease resistance in black tiger shrimp (Penaeus monodon)

The effects of commercially available Dunaliella extract (Algro Natural(R)) on growth, immune functions and disease resistance were determined in black tiger shrimp (Penaeus monodon). Trial I was performed in small shrimp (1-2 g body weight). Shrimp fed 125-300 mg of the Dunaliella extract/kg diet for 8 weeks showed higher weight gain and survival compared to the control. There was no significant difference in total hemocyte count and phenoloxidase activity among treatment. Shrimp fed 300 mg of the extract/kg diet exhibited higher resistance to WSSV infection than other groups and also became more tolerable to the stress (low dissolved oxygen condition). Color intensity of boiled shrimp was highest in groups fed 200-300 mg of the Dunaliella extract/kg diet. Trial II was performed in juvenile shrimp (12-15 g body weight) fed the same diet in Trial I for 6 weeks. Total hemocyte counts were negatively correlated to the increase in Dunaliella extract in test diet (r=-0.97). Phenoloxidase activity and clearance of pathogenic vibrio from the hemolymph were not significantly different. Total carotenoid and astaxanthin levels were highest in shrimp fed 200-300 mg of the Dunaliella extract. In conclusion, the Dunaliella extract showed beneficial effects as a shrimp feed supplement. (C) 2005 Elsevier B.V All rights reserved.