Ảnh hưởng của Probiotic lên hệ miễn dịch tự nhiên và sức đề kháng của cá Tra kháng bệnh gan thận mủ gây ra bởi Edwardsiella ictaluri

Antagonistic  activity  of  Bacillus  circulans  B3  (B3),  Bacillus  subtilis  N26.3  (N26.3), Pediococcus acidilactici LA61 (LA61) with Edwardsiella ictaluri were evaluated, and non-specific  immune parameters of  the striped  catfish  (Pangasianodon hypophthalmus),  and  its susceptibility  to  Edwardsiella  ictaluri  Gly09M  were  determined  when  the  fish  fed  diets 

containing single strains of B3, N26.3, LA61, and mixed strains (B3, N26.3, LA61) at 1x10 7 cfu/g of feed for 4 weeks. The results showed that B3, N26.3, and LA61 bacteria inhibited to E.  ictaluri  with  the  clear  zone  22.5  ±  0.7mm,  20.3  ±  0.6  mm,  ,  and  17.7  ±  1.5  mm, respectively. Fish fed a diet containing LA61 and mixed strains at 10 7 cfu g-1 had significantly 

higher survival rates than those fed the control diet after challenge with E. ictaluri Gly09M, causing  increases  in  the  survival  rates  of 22.2%  and  42,2%,  respectively,  compared  to  the control group. The phagocytic activity (PA) and respiratory burst of head kidney leucocytes of fish fed single strain diets and mixed strain diet at 10 7 cfu g-1 were significantly higher than those of fish fed the control diet after 4 weeks of feeding. However, phagocytic index (PI) had no significant difference between groups. Lysozyme activity of fish serum of fish fed LA61 and mixed strain diet at 10 7 cfu/g significantly increased compared to those of fish fed control diet,  and  had  increased  by  1,6-  and  2,3-fold,  respectively  compared  to  control  group. We therefore recommend dietary administration of mixed strains (B3, N26.3, and LA61) at 10 7cfu g-1 to enhance innate immunity and disease resistance of Pagasianodon hypophthalmus against Bacillary Necrosis of Pangasius (BNP) causing by E. ictaluri.