Effect Of Dietary Chitosan Supplementation On Antioxidant Function In Laying Breeders And The Underlying Mechanism

The present study was conducted to investigate the effect of chitosan on antioxidative function of laying breeders and underlying mechanism.The experiment adopted single factor completely random design.Four hundred and fifty egg yield(92.44%� 0.030)26-weeks-old Hy-Line brown laying breeders were randomly allotted to five dietary treatments with six replicates in each treatment and fifiteen laying breeders in each replicate.The laying breeders in the five treatments were fed the basal diet supplemented with 0(control),250,500,1'000 and 2000mg/kg chitosan.The experiment period contained pre-trial period of 1 week and trial period of 8 weeks.The experiment 1 was to elucidate the effects of chitosan on antioxidant parameters in serum,liver and duodenum of laying breeders.The experiment 2 was conducted to investigate the effects of chitosan on ARA metabolism and MAPK signal pathway in liver and duodenum,and to elucidate molecular mechanism for chitosan to modulate antioxidation function.The experiment 3 mainly researched the effects of chitosan on gene expressions of antioxidative enzyme and Nrf2 in liver and duodenum,further explored molecular mechanism for chitosan to modulate antioxidative function from transcription level of laying breeders.The results of this study showed as follows:?The dietary supplementation of chitosan improved the activity of GSH-Px,T SOD,TrxR and anti-superoxide anion in serum,liver and duodenum of laying breeders in a quadratic dose-response relationship.Laying breeders fed with chitosan at 2501 000mg/kg in the diet showed a greater antioxidant function in serum,liver and duodenum,whereas feeding 2000mg/kg of chitosan showed the progressive reductions,and even inhibited those antioxidative function.?The dietary supplementation of chitosan affected the activity of JNK and ERK1/2 in liver and duodenum of laying breeders and increased linearly with increasing addition of chitosan on 8th week,whereas the ARA and LTB4 content,cPLA2 activity increased quadraticlly in duodenum.The adding 250?500mg/kg of chitosan in diet showed the better effect,while feeding 2000mg/kg chitosan showed the progressive reductions.?Dietary supplementation of chitosan increased the expression of GSH-Px,SOD1,SOD2.TrxR1 and Nrf2 genes in liver and duodenum of laying breeders in quadraticlly trendency,and laying breeders fed with the diet containing 250?500mg/kg chitosan had the greater effects.However progressive antioxidantion genes expression reductions when the addition of chitosan to the diet was increased to 2000mg/kg.?The mechanisms for chitosan to affect antioxidant functions of laying breeders were probably that chitosan activated Nrf2 signal pathway by raising the expressions of Nrf2 and its downstream gene antioxidant enzymes,thereby enhancing antioxidant enzymes activity and antioxidant function of laying breeders.Chitosan regulated the production of ARA in duodenum by MAPK signal pathway,reducing oxidative stress and maintaining healthy metabolic status of laying breeders.?In conclusion,the laying breeders fed the diet containing 250?500 mg/kg chitosan had higher antioxidant function.