Effectiveness of Galactooligosaccharide and Combination of Yeast + Β-Glucan in Soybean Meal Diets on Innate Immune Response and Disease Resistance Against Aeromonas hydrophila in Striped Catfish (Pangasianodon hypophthalmus)

Feeding soybean meal (SBM) based diets affects fish gut immunity and causes significant tissue lesions that inhibit digestion and absorption. The addition of probiotic, prebiotics and their synbiotics used in SBM diets is assumed can mitigate the negative effect of SBM. This current study was carried out to investigate the effects of commercially available galactooligosaccharide (GOS) and combination of 1% yeast + 0.1% β-glucan (YβG) on haematological, immune response and disease resistance in striped catfish juvenile against Aeromonas hydrophila. Fish (average initial weight 16.45±0.07 g) were fed with four different diets up to 12 weeks containing control negative, control positive, 1 % GOS and combination of 1% yeast+0.1% β-glucan. After 12 weeks feeding trial, the fish were challenged intraperitoneally with 0.2×106 cfu/ ml of A. hydrophila. The haematological and immunological parameters were assayed both in pre-challenged and post-challenged groups. There was a significant improvement in red blood cell, haemoglobin concentration, white blood cell and granulocyte count in both supplemented groups over the control. Immunoglobulin level showed an increasing trend in pre-challenged fish but it was much higher in post-challenged fish. There was a significant increase in lysozyme activity and further significant increase in the levels of serum lysozyme occurred in fish injected with A. hydrophila. In conclusion, the supplementation of GOS and YβG could improve the health status of striped catfish based on the improvement of their haematological and immunological parameters as well as their ability to resist A. hydrophila infection.