Effects of Dietary Nucleotides on the Immune Response and Growth of Juvenile Pacific White Shrimp Litopenaeus vannamei (Boone, 1931)

Effects of dietary supplementation of nucleotides on immune response, survival against white spotsyndrome virus (WSSV) challenge infection and growth of Pacific white shrimp Litopenaeus vannamei (Boone, 1931) juveniles were evaluated. The basal diet for Pacific white shrimp supplemented with nucleotide formula (Vannagen; Chemoforma, Augst, Switzerland) at 0%, 0.2%, 0.4% and 0.6% kg^-1 of feed were tested. Survival of shrimp was in the range of 92-97% and was not significantly different among treatments. However, specific growth rate (SGR), feed conversion efficiency (FCE) and protein productive value (PPV) were significantly better in shrimps fed the nucleotide-supplemented diet than those fed the control diet after a 60-day feeding trial. Survival of test animals upon challenge with WSSV infection was significantly higher in the nucleotide group than in the control group. Immune response indices i.e. total haemocyte count (THC), respiratory burst activity and phenoloxidase activity were significantly enhanced in shrimp fed diets containing nucleotides as compared to those fed diets with no supplementation. At the levels tested, 0.2% nucleotide in the diet was the optimum. These results indicate that dietary supplementation of nucleotides resulted in beneficial effects in improving growth, feed utilisation, protein utilisation and accelerate shrimp immune response against WSSV infection.