Effect of dietary supplementation on improvement of growth and immune function of broilers

The purpose of this investigation was to evaluate the effect of a dietary supplement （Mirigen TM）, a fungal cell wall derivative product, as a new generation alternative to antibiotics, on the growth and the innate and adaptive immune functions in broilers from birth to 45 d of age. Newborn chicken were randomly assigned to one of three groups： G 1 （n=150） controls no supplement fed; G2 （n=150） is fed with dietary supplement at a designed regular dose （0.5 %, weight of additive to food）; G3 （n= 150） is fed with dietary supplement at double doses （1%）. All three groups were housed in the same conditions. Body weight and blood were taken on day 1, 14, 28 and 45. Medications used and costs/treatment were recorded for each group. The whole blood was used to purify heterophils for reactive oxygen species （ROS） generation and E coli killing abilities examination assays, and the serum samples were preserved in freezer for enzyme linked immunosorbent assays （ELISAs） to determine concentration of macrophage inflammatory protein-1β （MIP-1β）, CD4/CD8, interferon-y （IFN-y）, and titers of antibody against Newcastle disease virus （NDV）. Group differences were analyzed using analysis of variance （ANOVA） algorithm （S-Plus）. There was no significant birth weight difference in three groups. After 45 d growth, the dietary supplement treated groups had significantly higher body weight gain （BWG） with lower mortality rate if compared to the untreated control group （P〈0.05）. Their BWG and mortality rate were 2.23 kg and 10 % in GI （control group）, 2.89 kg and 2 % in G2 （experimental group, 0.5 % dose）, and 2.77 kg and 1% in G3 （experimental group, 1% dose）, respectively. Heterophil ROS generation in treated groups were markedly improved through the addition of dietary supplement in both regular and double doses to the diet （P〈 0.05）. The ability of heterophil to kill E coli was also significantly improved in dietary supplement treated groups （P〈0.01）. Comparing to control group, there was significantly higher serum IFN-y concentration in treated groups （P〈0.05） on day 45. The CD4/CD8 was also improved in treated groups （P〈0.05）. Newcastle di-sease is the most prevalent avian disease, and vaccination is an effective method to protect the animals from the virus infection. In our study, it is found G2 and G3 that fed with dietary supplement had higher antibody titers against NDV after vaccination （P〈0.01） and the antibodies lasted longer. Results from this study demonstrated dieta