Abstract: The experiment was designed to study the supplementing with different concentration of chitosan oligosaccharide on immune function of layer quails in diet.Selected 1 day old 240 Korean quails were divided into 6 groups randomly,2replicates in each group and 20 quails per replicate.Ⅰgroup was fed with the basal diet,Ⅱ、Ⅲ、Ⅳ、Ⅴ and Ⅵ groups were fed with the adding of 0.01%,0.05%, 0.10%, 0.15% and 0.20% chitosan oligosaccharide. Trial period was 35 days. The results showed that the chitosan oligosaccharide could significantly improve the quails bursal relative weight (P<0.05), significantly increase the relative weight of thymus and spleen relative weight (P<0.01),significantly improve the quails serum IgG and IgM content (P<0.05),maintain high serum antibody titer against Newcastle disease virus (P<0.05),significantly increase the content of complement C3 (P<0.05).Therefore,adding chitosan oligosaccharide could promote the growth and development of immune organs of quails and improve immunity,enhance the ability of resistance to infectious diseases, adding 0.05% chitosan oligosaccharide effect was the best.

Key words: chitosan oligochitosan; immune function; layer quails