Immunomulation effect of alginic acid and chitooligosaccharides in silver carp (Hypophthalmichthys molitrix)

Individual and combined efficacy of chitooligosaccharides (COS) and alginic acid (AA) at 1 g, 2 g, and 3 g per kg diet was assessed on growth and disease resistance in silver carp (Hypophthalmichthys molitrix) against Edwardsiella ictaluri. Growth parameters including specific growth rate (SGR), weight gain (WG), and feed conversion rate (FCR) were significant in fish fed 2 g and 3 g kg^-1 of COS or AA, and fish fed combined COS + AA at 1, 2 and 3 kg^-1 diet. In all groups, the survival rate (SR) was recorded 100%, except in group fed 2 g kg^-1 AA diet. All the hematological and biochemical profiles significantly increased in groups fed 2 g and 3 g kg^-1 of COS, AA, and COS + AA diets. Lipase and amylase enzyme activities and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPx) antioxidant enzyme activities were significantly increased in fish fed 2 g and 3 g kg^-1 of COS, AA, and COS + AA diet. Respiratory burst (RB), lysozyme (Lyz), reactive oxygen species (ROS) activities, and immunoglobuline (Ig) level were enhanced significantly in fish fed 2 g kg^-1 of COS or COS + AA and all 3 g kg^-1 diets, whereas nitric acid (NO) production and serum AP activity were improved in 2 g kg^-1 COS + AA and 3 g kg^-1 COS or COS + AA diets. Pro-inflammatory cytokine such as IL-8 mRNA transcriptions was significant in 2 g kg^-1 COS + AA diet and all 3 g kg^-1 diet. The IL-10 anti-inflammatory cytokine mRNA transcriptions were significant in 3 g kg^-1 COS or COS + AA diets. This study was confirmed that H. molitrix fed with 3 g kg^-1 COS or COS + AA diets were better activity when compared to other diet.