Dietary Sodium And Chloride Levels Affected Eggshell Quality And Ion Metabolism In Laying Hens

Eggshell quality improvement could be of considerable value to egg producers and poultry industry.Eggshell formation is the process of bicarbonate ion and calcium ion exchange and deposition,which is affected by ion metabolism and acid-base balance of body fluids.Sodium?Na?and chlorine?Cl?participate in the ion metabolism and acid-base balance of body.This dissertation mainly studied the effects of dietary sodium and chloride levels on eggshell quality and ion metabolism in laying hens by using sodium bicarbonate and sodium sulfate to replace partly sodium chloride in diets.Experiment 1:Effects of dietary Cl levels on production performance,egg quality,and blood biochemical in laying hens.A total of 360 28-wk-old Hy-Line Brown laying hens were fed a pre-trial diet?Experimental premix contains 0.33%sodium chloride,dietary 0.27%Cl and dietary 0.15%Na?for1 wks and then were randomly allocated to 5 dietary treatments that were fed a basal diet with 0.33%sodium choride?control?or the the basal diet with the experimental premix to meet the dietary Cl were0.21%and 0.15%?dietary 0.15%Na?by using sodium bicarbonate or sodium sulfate to replace partly sodium chloride,respectively.The results showed that dietary 0.21%and 0.15%Cl increased ADFI during wk 9 to 12 by using sodium bicarbonate?P<0.05?.Dietary 0.21%and 0.15%Cl increased egg production of wk 5 to 8,9 to 12 and 1 to 12 and yolk color by using sodium sulfate?P<0.05?.Dietary0.21%Cl decreased TP and ALP in blood significantly?P<0.05?.No damage to liver and kidney of laying hens was observed in this experiment.Therefore,decreasing dietary Cl levels can improve production performance of laying hens by using sodium bicarbonate or sodium sulfate instead of partly sodium chloride.Experiment 2:Effects of dietary Cl levels on eggshell quality and ion metabolism in laying hens.The trial design was the same as that of Experiment 1.Dietary 0.21%and 0.15%Cl increased eggshell breaking strength at wk 12 by using sodium bicarbonate?P<0.05?.Dietary 0.15%Cl decreased the tibial cross-sectional diameter,the contents of tibial Ca²⁺and Na⁺,and the content of Ca²⁺in manure at wk 12,and the contents of K⁺and Ca²⁺in blood,the pH value of blood at wk 6 by using sodium bicarbonate?P<0.05?,however,dietary 0.15%Cl increased tibial breaking strength and the content of Na⁺in blood at wk 6?P<0.05?.Dietary 0.15%Cl increased eggshell breaking strength,thickness,shell weight ratio,tibial breaking strength at wk 12 and the content of Na⁺in blood at wk 6?P<0.05?,however,dietary 0.15%Cl decreased tibial cross-sectional diameter,the contents of tibial Ca²⁺at wk 12and the contents of K⁺and Ca²⁺in blood,the pH value of blood at wk 6?P<0.05?.Therefore,decreasing dietary Cl levels?0.15%and 0.21%?can decreased tibial cross-sectional diameter and increased breaking strength of tibial and eggshell of laying hens by using sodium bicarbonate or sodium sulfate instead of partly sodium chloride.And we recommend the optional dietary Cl level is 0.15%.Experiment 3:Effects of dietary Na levels on production performance,egg quality,and blood biochemical in laying hens.A total of 576 28-wk-old Hy-Line Brown laying hens were fed a pre-trial diet?Experimental premix contains 0.33%sodium chloride,dietary 0.15%Na and dietary 0.27%Cl?for1 wks and then were randomly allocated to 8 dietary treatments that were fed the basal diet with the experimental premix to meet dietary total Na were 0.15%,0.25%,0.30%and 0.40%?dietary 0.15%Cl?by using sodium bicarbonate or sodium sulfate,respectively.The results showed that dietary Na levels did not affact the egg production?29 wk to 40 wk,P>0.05?.Linear and quadratic effects on yolk color and quadratic effect on haugh unit at wk 6 and no differences on egg quality at wk 12 were observed with increasing dietary Na by using sodium bicarbonate?P<0.05?.Linear and quadratic effects on yolk color at wk 12 were observed with increasing dietary Na by using sodium sulfate?P<0.05?.Additionally,dietary 0.40%Na decreased TP and CRE significantly by using sodium sulfate?P<0.05?.Compared with sodium bicarbonate,sodium sulfate increased albumen height significantly?P<0.05?.No damage to liver and kidney of laying hens was observed with dietary Na between 0.15%and 0.30%.Therefore,we recommend the optional level of dietary Na are 0.15%⁰.30%?dietary 0.15%Cl?.Experiment 4:Effects of dietary Na levels on eggshell quality and ion metabolism in laying hens.The trial design was the same as that of Experiment 3.Increasing dietary Na level resulted in quadratic increases of breaking strength?NaHCO₃,P=0.028;Na₂SO₄,P=0.005?,uronic acid content of membrane?Na₂SO₄,P=0.073;NaHCO₃,P=0.024?,the contents of Na⁺,Cl^-,K⁺in blood at wk 6?P<0.05?,and pH value of blood?NaHCO₃,P=0.072;Na₂SO₄,P=0.001?.The sulfated GAGs content of membrane was increased linearly with increasing dietary Na level?P<0.05?.Linear and quadratic effects on the contents of Na⁺,Cl^-in blood,the pH value of blood,and the content of Na⁺in manure at wk 6 were observed with increasing dietary Na level?P<0.05?.Dietary 0.30%Na increased eggshell breaking strength?NaHCO₃,P=0.067;Na₂SO₄,P<0.001?,tibial breaking strength and the effective thickness?P<0.05?,however,dietary 0.30%Na decreased the mammillary thickness and mammillary knob width?P<0.05?.Linear effect on the contents of Ca²⁺in blood at wk 6 and quadratic effect on the content of Ca²⁺in blood and manure at wk 12 were observed with increasing dietary Na level by using sodium bicarbonate?P<0.05?.Moreover,dietary 0.30%Na increased the content of Na⁺,Cl^-,Ca²⁺in blood and the pH value of blood?P<0.05?,but decreased the K⁺content in blood significantly?P<0.05?by using sodium bicarbonate.In sodium sulfate groups,quadratic effect on the eggshell weight ratio at wk 12 were observed with increasing dietary Na level?P<0.05?.Dietary 0.30%Na increased shell thickness,weight ratio and manure Ca²⁺content at wk 12,blood pH value and K⁺content at wk 6?P<0.05?.However,dietary 0.30%Na decreased the contents of Na⁺and Cl^-in blood?P<0.05?.Compared with sodium bicarbonate,sodium sulfate increased eggshell thickness,breaking strength and shell weight ratio?P<0.05?.Sodium sulfate groups had increased trends on the effective thickness?P=0.060?,mammillary knob width?P=0.069?,blood Na⁺content?P=0.078?compared with sodium bicarbonate groups.However,sodium sulfate groups decreased tibial breaking strength and blood Ca²⁺content?P<0.05?.Therefore,we recommend the optional level of dietary Na was 0.30%?dietary0.15%Cl?,which can obtained better eggshell quality,and sodium sulfate was better than sodium bicarbonate.Overall,decreasing dietary Cl levels can improve production performance and eggshell quality of laying hens by using sodium bicarbonate or sodium sulfate instead of partly sodium chloride.And we recommend the optional level of dietary Cl level is 0.15%.Dietary 0.30%Na increased breaking strength by improving the ultrastructure when the dietary Cl level was 0.15%,which partly resulted from increased sulfated GAGs and uronic acid contents in the membrane.And Na₂SO₄-fed hens can obtained better eggshell quality by increasing the effective thickness and the sulfated GAGs content of calcified eggshell compared with NaHCO₃-fed hens.