Study On The Effect And Mechanism Of Electrolyzed-reduced Rich-hydrogen Water On Relieving Chronic Heat Stress In Laying Hens

High environmental temperature cause acute or chronic heat stress in laying hens.Adding antioxidants to the diet is a common way to alleviate heat stress.Water consumption will increase under heat stress（HS）unlike feed intake therefore,supplementary antioxidants by drinking method may be better than feeding.Electrolyzed-reduced rich-hydrogen water（ERW）,with high reductive efficiency,can neutralize reactive oxygen species（ROS）in the body.And it has been proven to be a cheap and safety drank water.However,it is not known whether ERW might mitigate damage to layers exposed to HS therefore,three experiments was conducted as following:Exp 1:Effect of drinking ERW on the performance and egg quality of laying hens at normal environmental temperature.A total of 80 27-week-old white Leghorn laying hens,with nearly the same body weight,were randomly divided into two groups（normal temperature（NT）;normal temperature+ERW（HT+ERW））.Each treatment had 40 layers and assigned to 5replicates（8 layers/replicate）,and 2 hens were housed in a cages（36×30×35 cm）.The drinking trial lasted for 45 days after 1-weeks of adaptation period.Layer’s production performance,egg quality,plasma biochemical indexes and intestinal morphology were checked.Exp 2:Effect of drinking ERW on the performance and egg quality of laying hens under high environmental temperature.A total of 80 27-week-old white Leghorn laying hens,with nearly the same body weight,were randomly divided into two groups（high temperature（HT）;high temperature+ERW（HT+ERW））.Each treatment had 40 layers and assigned to 5replicates（8 layers/replicate）,and two hens were housed in a cages（36×30×35 cm）.The drinking trial lasted for 45 days after 1-weeks of adaptation period.Experiment 2conducted under high environmental temperature,and other conditions were basically similar to experiment 1.Layer’s production performance,egg quality,plasma biochemical indexes and intestinal morphology were checked.Exp 3:The anti-apoptotic effect of ERW on primary liver cell of laying hens induced by H₂O₂.Explore the establishment of oxidative stress model of laying hen primary liver cell induced by H₂O₂ and the anti-apoptotic effect of ERW.The primary laying hen primary liver cell were treated with conventional medium or ERW medium（the medium was prepared with ERW）for 24 h,and then treated with differentconcentrations of H₂O₂（200,300,400 and 500μmol/L）and ERW+H₂O₂（200,300,400and 500μmol/L）for 2 h.The survival rate of layer primary liver cell and the expression of ROS and enzyme antioxidant system were detected.Results:1.Drinking with ERW had no effect on feed intake and water consumption（P>0.05）,and no significant differences were observed in production performance,egg quality,plasma enzyme activity and intestinal morphology of laying hens under NT（P>0.05）.2.In summer high temperature,drinking with ERW increased laying rate（P=0.073）and eggshell thickness（P=0.067）,significantly increased plasma T-AOC（P<0.05）,decreased MDA（P<0.05）,increased jejunal villus height,and significantly increased jejunal V/C（P<0.05）.3.A concentration of 400μmol/L was chosen as the H₂O₂ experimental dose.Treatment with ERW attenuated H₂O₂-induced（400μmol/L）ROS and MDA（P<0.05）,increased SOD,CAT and GSH-Px（P<0.05）,and ameliorated cell apoptosis in r primary liver cell from layers.Conclusion:Based on our study,we can conclude that drinking with ERW could increase the total antioxidant capacity,decrease the generation of MDA damage,protect the muscle and organs of layers from ROS-induced oxidative damage,and consequently improve the production performance and egg quality of layers high environmental temperature.Molecular hydrogen,with dissolve in ERW,may acts as a therapeutic antioxidant by selectively reducing ROS.