| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2433395 | Fish & Shellfish Immunology | 2007 | 13 Pages |
The total haemocyte count (THC), phenoloxidase activity, and respiratory burst were examined when white shrimp Litopenaeus vannamei were immersed in seawater (34‰) containing hot-water extract of red alga Gelidium amansii at 200, 400 and 600 mg l−1, injected with hot-water extract at 4 and 6 μg g−1 shrimp, and fed diets containing hot-water extract at 0, 0.5, 1.0 and 2.0 g kg−1. These parameters increased significantly when shrimp were immersed in seawater containing hot-water extract at 400 and 600 mg l−1 after 1 h, when shrimp were injected with hot-water extract at 6 μg g−1 shrimp after one day, and when shrimp were fed diets containing hot-water extract at 1.0 and 2.0 g kg−1 after 14 days. Phagocytic activity and clearance efficiency were significantly higher for the shrimp that were fed diets containing hot-water extract at 1.0 and 2.0 g kg−1 than those of shrimp that were fed diets containing hot-water extract at 0 and 0.5 g kg−1 after 14 and 28 days. In a separate experiment, L. vannamei which had received hot-water extract via injection, or fed diets containing hot-water extract, were challenged after 3 h or 28 days with V. alginolyticus at 2 × 106 cfu shrimp−1 and 1 × 106 cfu shrimp−1, respectively, and then placed in seawater. The survival of shrimp that were injected with hot-water extract at 6 μg g−1 was significantly higher than that of control shrimp after 1 day, and the survival of shrimp fed diets containing hot-water extract at 0.5, 1.0 and 2.0 g kg−1 increased significantly after 3 days as well as at the end of the experiment (6 days after the challenge), respectively. It was concluded that L. vannamei that were immersed in hot-water extract at 400 mg l−1, injected with hot-water extract at 6 μg g−1 shrimp, and fed hot-water extract of G. amansii at 2.0 g kg−1 or less showed increased immune ability as well as resistance to V. alginolyticus infection.
