Effects Of Chitosan On Laying Performance, Immune And Antioxidative Function And Serum Biochemical Indexes In Laying Hens

The present experiment was conducted to study the effects of different levels of chitosan in diet on production performance, egg quality, lipid metabolism, immune and antioxidative function and blood biochemical indexes of laying hens, in order to provide a theoretical basis for chitosan application in poultry diets. According to the principles of similar body weight and laying rate,450 healthy 26-week-old Hy-line brown hens were selected and divided randomly into 5 dietary treatment groups, each with 6 replicates in which 15 hens were included. The control group was fed with the basal diet, and the diets of test groups were added with, resPectively,250,500,1000,2000 mg/kg chitosan on the basis of control diet. The experimental period contained a pre-trial period of 7 days and a test period of 8 weeks which was divided into two periods equally, each lasting 4 weeks. For the five experimental groups, the environmental conditions and feeding and management are consistent. The results were shown as follows:Dietary supplementation of chitosan quadratically improved the egg laying rate of laying hens during the earlier period and latter period (P<0.05). And dietary chitosan increased linearly the fertilization rate in the whole period of laying hens (P<0.05).Dietary supplementation of chitosan quadratically improved the white height of eggs at wk 8 (P<0.05) and Haugh units showed a highly significant quadratic increase effects (P <0.01)at wk 8.Dietary supplementation of chitosan linearly reduced the ether extract (EE) of yolk at wk 4 and 8 (P<0.05), but had no significant impact on other indicators. With the increase of dietary supplementation of chitosan, the content of cholesterol (CHO) in yolk linearly or quadratically reduced at wk 4, (P<0.01) and linearly or quadratically reduced at wk 8 (P<0.05); the content of triglyceride (TG) in yolk linearly or quadratically reduced, at wk 4 (P<0.01) and wk 8 (P<0.05); in addition, total superoxide dismutase (T-SOD) activity in yolk showed a significant linear or quadratic increase effects at wk 4 and 8 (P< 0.05); malonaldehyde (MDA) levels in yolk of chitosan groups, were lower than those of the control group and 500 mg/kg chitosan group had the lowest level of MDA, and a significant linear decrease trend was showed at wk 8 (P=0.054).With increasing chitosan, serum T-SOD activity increased in quadratic manner at wk 4 and wk 8 (P<0.05); the serum MDA content quadratically reduced at wk 4 (P<0.05), and reduced linearly or quadraticlly at wk 8 (P<0.01); the serum IgA content quadratically increased at wk 8 (P<0.05); serum IgM content was enhanced in linear or quadratic manner at wk 4 (P<0.05), and was enhanced in quadratic manner at wk 8 (P<0.05).Dietary supplementation of chitosan linearly or quadratically reduced serum CHO level at wk 4 and wk 8 (P<0.01), and linearly (P<0.05) or quadratically (P<0.01) increased serum high density lipoprotein cholesterol (HDL-C) content at wk 4. With increasing chitosan, serum low density lipoprotein cholesterol (LDL-C) content was reduced in a quadratic manner at wk 4 (P<0.05), and serum TG content was quadratically reduced at wk 4 and wk 8 (P<0.05).