Ảnh hưởng của chất chiết từ lá cây hoàn ngọc (Pseuderanthemum palatiferum (Wall.) Radlk) lên tăng trưởng và đáp ứng miễn dịch cá tra (Pangasianodon hypophthalmus)

Abstract

This study was conducted to observe the impact of dietary supplementation of Pseuderanthemum palatiferum (Wall.) Radlk leaf extract on growth and non-specific immune response of striped catfish (Pangasianodon hypophthalmus). The experiment was randomly designed with 4 triplicated treatments including 0%, 0.02%, 0.1%, and 0.5% Pseuderanthemum palatiferum (Wall.) Radlk leaf extract. Total red blood cells, total white blood cells, lymphocytes, monocytes, neutrophils, thrombocytes and lysozyme activities were observed for immune responses at the 3rd and the 6th week post-feeding and the 3rd day post challenge with pathogenic bacteria. The results showed that the treatments of supplemented 0.02%, 0.1%, and 0.5% extract did not significantly affect the growth of striped catfish. The total red blood cell and total white blood cell counts significantly increased in supplemented extract treatments if compared to the control. After 6-week feeding, lysozyme activity was highest (90,7 mg/mL) in treatment of 0.5%. After challenge with Edwardsiella ictaluri, the results indicated that mortality rates in 0.1% and 0.5% treatments were lower than those of the control treatment. These results suggested that the supplemention of Pseuderanthemum palatiferum (Wall.) Radlk leaf extract in diets could improve the immune responses and reduce the mortality of striped catfish after being challenged with E. ictaluri.