| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 103 === White shrimp Litopenaeus vannamei juveniles (2.15±0.16g) which had been fed control diet and a diet containing Gracilaria tenuispitata extract at 1.0 g kg-1 for 16 weeks were examined for the growth, immune parameters of shrimp and its resistance against Vibrio alginolyticus and V. harveyi. Four feeding strategies were carried out. They were (1) shrimp fed control diet contiunously (C4). (2)shrimp fed extract containing diet contiunously (G4). (3) shrimp fed extract containing diet three weeks and then fed control diet one week (G3-C1). (4) shrimp fed extract containing diet two weeks and then fed control diet two weeks (G2-C2). Shrimp in G4 grew faster than other groups. Hyaline cells (HC), granular cells (GC), total haemocyte count (THC), respiratory burst (RB), superoxide dismutase (SOD) activity, lysozyme activity, proteion concentration, hemocyanin, and transcript levels of immune-related proteins of shrimp were higher with less clotting time in G2-C2. In another experiment, shrimp fed in four different feeding strategies for 16 weeks were challenged with V. alginolyticus and V. harveyi. Survival rate of shrimp in G4 was significantly higher than that of other groups over 24-144h. Phagocytic activity and clearance efficiency of shrimp to V. alginolyticus and V. harveyi were higher in G4. In conclusion, shrimp in G2-C2 showed increased resistance to Vibrio as evidenced by higher immune parameters and higher immune gene expressions. Shrimp in G4 still showed a protective resistance against Vibrio despite that its same immune parameters with C4.
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