| The complex polyphenols and chemical structures of tannins lead to diverse biological activities.It is still unclear that if the response of nutrition and physiology of hens to Gallotannic acid(GTA)and Gallic propyl(PG)is different,due to different chemical structures between GTA and PG.Studies hint that TA have the potential to prevent fatty liver syndrome of laying hens,but there is few reported.Hence,the effects of GTA and PG addition on egg-laying performance,egg quality,nutrient metabolites,anti-inflammatory and immune function were studied to reveal the regulation of TA with different chemical structures;the dose responses of GTA to production performance,egg qualities and fat metabolism in layers were analyzed to select the optimal level of Gallic tannins for preventing fatty liver by.The study was expected to offer supports for TA applied in hens production.The study contained 3 parts:Trial 1 Effects of gallnut tannic acid(GTA)and propyl gallate(PG)on laying performance,egg quality,blood biochemical indexes in layers during the peak laying period.The 1500 Lohmann layers aged 34 week-old were randomly divided into 3 treatment groups,with5 replicates for each treatment,and 100 chickens for each replicate.The treatment were control group(without GTA and PG addition),300 mg/kg GTA addition,and 300 mg/kg PG addition.The results showed that:1)either GTA or PG additions enhanced egg yolk color(P<0.01);2)GTA or PG tended to decrease blood glucose levels(0.1>P>0.05),GTA addition significantly reduced the plasma TC(P<0.05),TG(P=0.077),HDL-C(P=0.077),LDL-C content,TP,ALB and GLB contents(P<0.05),and PG addition just numerically decreased TP and ALB contents(P>0.05);3)GTA addition reduced serum IL-1β,IL-6 and TNF-α(P<0.05),and PG improved serum Ig Y and Ig M levels(P<0.05).In conclusion,either 300 mg/kg GTA or PG addition improved the egg yolk coloration,and contents of glucose,lipids,and proteins from blood were decreased with GTA and PG supplementation.The GTA inhibited the serum inflammatory factors secretion,and PG promoted immunity of hens.Trial 2 Impact of GTA on laying performance,egg quality,blood biochemical and liver lipid metabolism in layers during the late laying period.The 360 aging 420-day-old Lohmann layers were selected and randomly divided into 4 groups with 5 replicates per treatment and 16hens per replicate.Hens fed with 0,100,300 and 900 mg/kg GTA diet,respectively.The results showed that:1)300 mg/kg GTA inclusion improved egg production rate(P<0.05);2)GTA addition had no effect on egg quality,eggshell quality and yolk nutrients(P>0.05);3)Blood glucose,TG and TC contents were decreased with increasing GTA addition level(P<0.05);4)GTA addition significantly inhibited TNF-αlevels(P<0.05),and GTA 300 and GTA 900 inhibited IL-8 secretion in layers(P<0.01);4)Hepatic OH~-and O2.~-were reduced by GTA(P<0.05).4)GTA addition significantly decreased liver lipid ratio,liver TG and TC content(P<0.05).In conclusion,GTA addition enhanced egg production rate,decreased blood glucose and lipids levels,inhibited inflammatory reaction and oxygen free radical production,hinder fat deposition in liver.Trial 3 Lipid metabolism regulation of GTA on liver of laying hens by lipidome analysis.Twenty hens were selected from the control and GTA 300 groups in Trial 2,respectively,and liver were sampled and stored in liquid nitrogen for lipidome analysis.A total of 35 lipid subclasses and 1437 lipid molecules were identified,in which 5 were lipids,and 14 lipid subclasses were affected by GTA.The GTA addition down-regulated contents of MG(P<0.05),DG(P<0.01)and TG(P<0.01)in glycerides,PI(P<0.01),PA(P<0.01)and LPI(P<0.01)in glycerophosphate,Ch E(P<0.01)and Zy E(P<0.001)in sterols,and GM3 and Cer G2GNAc1(P<0.01)in sphingolipids;and increased contents of PS(P<0.001)and PG(P<0.001)glycerophosphates,and OAHFA and WE(P<0.01)in fatty acid acyls.The GTA decreased unsaturated fatty acids contents in DG,TG,PI,Ch E,Cer G2GNAC1,LPI,OAHFA,PC and Zy E,while unsaturated fatty acids contents in PS and WE were increased.In conclusion,(1)either GTA or PG addition improved egg yolk coloration;(2)GTA addition inhibited the secretion of inflammatory factors,while PG enhanced immunity;both GTA and PG addition reduced blood glucose and blood lipid levels in laying hens,but the down-regulated range of GTA addition was more significant than PG;(3)The 300 mg/kg GTA diet improved the laying rate of laying hens in the late laying period,inhibited the generation of inflammatory factors and liver free radicals,reduced the deposition of glycerides,glycerophospholipids,sphingolipids and steroids in the liver,decreased saturated fatty acids contents,and altered liver lipids.qualitative ingredients. |
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