Effect of oligochitosan and oligo-ß-glucan supplementation on growth, innate immunity, and disease resistance of striped catfish (Pangasianodon hypophthalmus).

Oligochitosan (COS) and oligo-ß-glucan (ßOG) were prepared by gamma Co-60 irradiation of chitosan/H2 O2 and ß-glucan/H2 O2 solutions. The striped catfish (Pangasianodon hypophthalmus) was fed diets containing 0-200 mg COS, ßOG, and a mixture of COS/ßOG per kg feed for 45 days, and then challenged with Edwardsiella ictaluri bacterium. The effects of supplemented COS, ßOG, and a mixture of COS/ßOG on immune stimulation and growth performance in striped catfish were investigated. The results indicated that when striped catfish fed with 100-200 mg COS or ßOG/kg feed the growth performance was significantly improved and the mortality was considerably decreased. Furthermore, striped catfish fed with supplementation of 50 mg COS + 50 mg ßOG/kg feed was the best for increasing weight gain (∼26%) and for decreasing mortality (∼38%) compared with the control group. Moreover, phagocytic activity and lysozyme activity of fish were enhanced by feeding diet-supplemented COS and/or ßOG. Thus, COS and/or ßOG can be potentially utilized as the immunostimulants and growth promoters for aquaculture.