Lactobacillus acidophilus Supplementation Improves the Innate Immune Response and Disease Resistance of Striped Catfish (Pangasianodon hypophthalmus Sauvage, 1878) Juveniles against Aeromonas hydrophila

Abstract

A bacterium Lactobacillus acidophilus (LAB) was evaluated for its probiotic potential on the health status of striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878) juveniles. Triplicate groups of striped catfish (21.69 ± 0.18 g) were fed twice daily at 2.5 % of body weight, with 0 (control), 103, 105, 107 and 109 CFU/g LAB diets for 12 weeks. The fish were challenged intraperitoneally with 1×106 CFU mL−1 of Aeromonas hydrophila after 12 weeks of feeding trial and the mortalities were recorded over 21 days. The haematological, immunological parameters and histopathological changes of liver were assessed both in pre- and post-challenged fish groups. Results revealed that feeding the fish with supplemented diets significantly increased (p < 0.05) the survival after challenged with A. hydrophila. Compared to the control diet, a significant improvement in packed cell volume, red blood cell, white blood cell and lymphocyte counts were observed in LAB supplemented diets in the pre-challenged fish groups. After 3-week post challenged, the hematological parameters, immunoglobulin and survival were significantly high in fish fed with LAB supplemented diets at 105 CFU/g and above, while only the lysozyme activity was significantly high after 2-week post-infection. Histopathological result revealed that severe necrosis was found in the liver of striped catfish fed with the control diet after challenged with A. hydrophila which was not seen in the case of LAB supplemented diets. Thus, the results suggest that administration of LAB at 105 CFU/g of diet improves the innate immune response of striped catfish juveniles. HIGHLIGHTS Dietary Lactobacillus acidophilus (LAB) supplementation improved survival of striped catfish after challenge with Aeromonas hydrophila LAB supplementation enhanced the non-specific immunity of juvenile’s striped catfish LAB supplementation improved the histopathology of pre- and post-challenge liver of striped catfish juveniles GRAPHICAL ABSTRACT