Effects of Chitosan Oligosaccharides Supplementation on the Cell Cycle of Immune Organs in Broilers

The objective of this study was to investigate effects of COS on cell cycle and relative weights of thymus, bursa of fabricius (BF) and spleen in broilers. Three hundred and sixty 1-day-old healthy Arbor Acres male broilers were randomly divided into control, COS I, COS II and COS III groups, which were respectively fed with diets containing 0, 200, 350 and 500 mg/kg COS for six weeks. The results showed that the relative weights of immune organs were higher in the COS group II than those in the control group at 42 d. When compared with the control group, increased percentages of G(2)/M phase thymocytes in the COS groups II and III at 21 d, and decreased percentage of G(0)/G(1) phase cells, increased percentage of G(2)/M phase cells and PI (proliferation index) of thymus were observed at 42 d. The percentage of G(0)/G(1) phase BF cells was lower, and the percentage of S phase cells and PI of BF were higher in the COS group II at 21 d. The increase of G(2)/M phase splenocytes and PI, decrease of G(0)/G(1) phase splenocytes in the COS group II could be seen at 42 d.