Effects of dietary supplementation of chitosan on humoral and cellular immune function in weaned piglets

The effects of dietary supplementation of chitosan on humoral and cellular immune function in weaned piglets were investigated. One hundred and eighty piglets weaned at 28 d (Duroc × Large white × Landrace) were assigned randomly to 5 dietary treatments with 6 repetitions in each treatment. The piglets in the 5 treatments were fed on the basal diet supplemented with 0 (control), 100, 500, 1000 and 2000 mg chitosan/kg feed. Results showed that chitosan improved serum immunoglobulin G (IgG) concentrations of piglets in a quadratic dose-dependent manner (P<0.05), and increased serum specific ovalbumin (OVA) IgG contents in a linear or a quadratic dose-dependent manner (P<0.05) on day 28, while serum immunoglobulin A (IgA) and immunoglobulin M (IgM) concentration were not altered. With increasing chitosan, the secretory immunoglobulin A (sIgA) was enhanced in ileum mucosal surfaces in a linear or quadratic manner (P<0.05) on day 14, and was improved quadratically in jejunum mucosal surfaces on day 28 (P<0.05). In addition, chitosan decreased serum concentrations of soluble CD4 (sCD4) in a quadratic dose-dependent manner (P<0.05) and soluble CD8 (sCD8) in a linear or quadratic dose-dependent manner (P<0.05) on day 28. Chitosan quadratically enhanced serum concentrations of interleukin-1 (IL-1) and interleukin-2 (IL-2) on day 14 as well as serum concentrations of tumor necrosis factor-alpha (TNF-α) on day 28 (P<0.05). These results implied that dietary supplement with chitosan improved humoral and cellular immune responses of weaned piglets in a dose-dependent manner, and in this experiment, the appropriate adding dose of chitosan might be between 500 and 1000 mg/kg.