Effects of dietary algae (Sargassum ilicifolium) as immunomodulator and growth promoter of juvenile great sturgeon (Huso huso Linnaeus, 1758)

This study investigated the effects of dietary Sargassum ilicifolium on growth performance, hematological parameters, immune responses, and protection against Yersinia ruckeri challenge in great sturgeon, Huso huso. The fish (56.8 +/- 4.1g) were fed diets containing four concentrations of S. ilicifolium (0 (basal diet), 5, 7.5, and 10%) for 8weeks. Growth parameters were significantly (p<0.05) higher in 10% S. ilicifolium fed group after 8weeks of feeding trial. The same group contained significantly higher serum immunological activities such as serum total protein, lysozyme, immunoglobulin M, respiratory bursts, and complement activities. Among hematological parameters, hemoglobin levels, red blood cells, and white blood cells were significantly higher in group supplemented with 10% of S. ilicifolium. Administration of S. ilicifolium had no significant effects on blood biochemical parameters such as triglycerides, lactase dehydrogenase, aspartate aminotransferase, and alanine aminotransferase activities. However, 10% S. ilicifolium supplementation significantly lowered blood cholesterol levels. Furthermore, fish fed 10% S. ilicifolium supplemented diet exhibited the highest (p<0.05) relative post-challenge survival (75.2%) against Y. ruckeri infection. Overall, these results suggest that dietary supplementation of S. ilicifolium (at 10%) can promote growth and strengthen immunity of great sturgeon.