This experiment was conducted to study the effects of modified palygorskite(MPal)on perform-ance,egg quality,body mineral element content,mineral element related protein content and enzyme activity of Hy-Line Brown laying hens.A total of 448 Hy-Line Brown laying hens of 38-week-old were randomly di-vided into 4 groups with 8 replicates per group and 14 hens per replicate.The hens were fed the basal diet sup-plemented with 0(control),250,500 and 1 000 mg/kg MPal,respectively,which was the same in the early experiment(1 to 37 weeks of age).The pre-trial period was 2 weeks,and the trial period was 7 weeks.The results showed as follows:1)with the increase of dietary MPal level,the laying rate of laying hens had a quadratic change(P＜0.05).Compared with the control group,dietary 250 mg/kg MPal significantly in-creased the laying rate(P＜0.05).2)With the increase of dietary MPal level,the eggshell strength of laying hens had a quadratic change(P＜0.05),the mammillary knob width and palisade layer thickness of eggshell had linear and quadratic changes(P＜0.05),and the mammillary layer thickness of eggshell had a quadratic change(P＜0.05).Compared with the control group,dietary 250 and 500 mg/kg MPal significantly increased the eggshell strength and palisade layer thickness(P＜0.05).3)With the increase of dietary MPal level,the manganese(Mn)content in egg yolk and the contents of iron(Fe),Mn and phosphorus(P)in tibia of laying hens had linear and quadratic changes(P＜0.05),and the zinc(Zn)content in egg yolk,P content in plas-ma,Fe content in liver and calcium(Ca)content in tibia had quadratic changes(P＜0.05);the metallothio-nein(MT)Ⅰ mRNA relative expression level in liver of laying hens had a linear change(P＜0.05),and the MTⅣ mRNA relative expression level in ileum had a quadratic change(P＜0.05).Compared with the control group,dietary 250 and 500 mg/kg MPal significantly increased the contents of Fe and Ca in tibia,the MT ⅠmRNA relative expression level relative expression level in liver and the MTⅣ mRNA relative expression level in ileum(P＜0.05).4)With the increase of dietary MPal level,the transferritin(TRF)content in plasma and liver of laying hens had linear and quadratic changes(P＜0.05),and the activities of alkaline phosphatase(AKP)and copper zinc superoxide dismutase(Cu/Zn-SOD)in liver had quadratic changes(P＜0.05);the manganese superoxide dismutase(Mn-SOD)activity of in eggshell gland of laying hens had a linear change(P＜0.05).Compared with the control group,dietary 250 mg/kg MPal significantly increased the activities of AKP and Cu/Zn-SOD in liver(P＜0.05).In conclusion,long-term supplementation of MPal with appropriate level can improve the performance of laying hens,improve the submicroscopic structure of eggshell,enhance the eggshell strength,and increase the content of related proteins and enzyme activities by increasing the miner-al element contents in the body.Under the conditions of this experiment,the optimal supplemental level of MPal in diets for Hy-Line Brown laying hens is 250 mg/kg.[Chinese Journal of Animal Nutrition,2023,35(12):7735-7747]
modified palygorskitelaying hensperformanceegg qualitysubmicroscopic structure of egg-shellmineral elements
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