Effects Of Dietary Choline And Schizochytrium Oil On Docosahexaenoic Acid Deposition Efficiency Enrichment In Chincken Eggs

To evaluate the effect of dietary choline and Schizochytrium oil on enrichment efficiency of the docosahexaenoic acid?DHA?in the egg yolk and related lipid metabolism in laying hens.Experiment 1:Effect of dietary Schizochytrium oil supplementation on DHA enrichment in egg yolk.Four hundred and fifty laying hens of 28 weeks of age were allotted into 5 treatments groups with 6 replicates of 15 birds each.The control group was fed soybean meal-corn basal diet,and 4 of the experiment diets included 0.25%,0.50%,1.00%,and 1.50%of SO.All the birds were fed the basal diet in the control group for 7 days.The experimental period lasted 56 days.The results showed that the yolk color linearly increased with actual SO intake?P<0.05?.The supplemental level of SO resulted in quadratic increase in n-3 polyunsaturated fatty acid?PUFA?and DHA content?P<0.05?,while significantly linear reduces in n-6 PUFA?P<0.01?content of egg yolks at the end of feeding trial.Compared with the control group,the n-3 PUFA content in yolk increased by 173.98 mg/egg in the SO_1.50 group,and the DHA content in yolk increases by 163.24mg/egg?P<0.05?.The DHA content per egg linearly increased with actual DHA intake?P<0.05?,while the DHA enrichment efficiency was significantly,linearly and quadratically decreased?P<0.01?.The DHA enrichment efficiency among the dietary SO supplementation followed by25.08%,20.21%,13.68%,11.97%.A supplement of 0.795%SO was optimal of their sources respectively.Experiment 2:Effect of dietary choline,monoethanolamine and lysophosphatidylcholine supplementation on DHA enrichment in egg yolk.Four hundred and thirty-two 28-week-old laying hens were randomly allocated to one of the 6 dietary treatments,each treatment with 6 replicates of 12 birds each.All diets included 2%Schizochytrium powder.The control group was not supplemented with any additional phospholipids-substrates,whereas the other 5 experimental diets were supplemented with 0.01%choline?2.0 mmol/kg?,0.022%monoethanolamine?MEA,2.0mmol/kg?,0.177%lysophosphatidylcholine?LPC,2.0 mmol/kg?,0.0887%LPC?1.0mmol/kg?+0.011%MEA?1.0 mmol/kg,LPC+MEA?,or 0.025%Choline?1.0 mmol/kg?+0.011%MEA?1.0 mmol/kg,Choline+MEA?.The experimental period lasted 28 days.The results showed that the Choline and LPC groups had very higher n-3 PUFA and DHA levels than the other groups at d 28?P<0.01?.The DHA content of 144.70 mg/egg was observed for the control diet,while the DHA content of 161.02 mg and 166.20 mg per egg was observed for supplementation with Choline and LPC,respectively.The DHA content in egg yolk reached a plateau after the laying hens consumed the experimental diets for 14 days,and higher yolk DHA contents were observed in the Choline and LPC groups as compared with the other groups at d 14.Experiment 3:Effect of dietary choline and Schizochytrium oil levels on DHA content in egg yolk and egg quality under refrigetation condition.Six hundred and thirty 28-week-old laying hens were randomly divided into 7 groups of 6 replicates each and 15 birds in each replicate.Seven isonotrogenous and isocaloric diets were supplemented with 0.05%choline(Choline_0.05,control),0.1%choline+0.5%SO(Choline_0.1-SO_0.5),0.1%choline+1.0%SO(Choline_0.1-SO_1.0),0.1%choline+1.5%SO(Choline_0.1-SO_1.5),0.15%choline+0.5%SO(Choline_0.15-SO_0.5),0.15%choline+1.0%SO(Choline_0.15-SO_1.0),and 0.15%choline+1.5%SO(Choline_0.15-SO_1.5),respectively.All the birds were fed the basal diet in the control group for 7 days.The experimental period lasted 84 days.The results showed that the supplemental level of SO resulted in increase in egg yolk color?P<0.05?.The amounts of n-3 PUFA and DHA per egg were found to extremely significant increase with dietary SO supplementation?0.5%¹.5%,P<0.01?,while the enrichment efficiency of the n-3 PUFA and DHA in the yolk was extremely significant decreased?P<0.01?.The Choline_0.15 group improved the enrichment efficiency of DHA in yolk compared to the Choline_0.1group?P<0.05?.Dietary choline supplementation increased the enrichment efficiency of DHA in yolk of laying hens fed a 0.5%Schizochytrium oil-added diet?P<0.05?.The DHA enrichment efficiency is 34.01%when birds fed Choline_0.15-SO_0.5.5 diet.The supplement of 0.601%and 0.449%SO were optimal of their sources respectively when dietary supplementation with 0.1%and 0.15%choline.The yolk color of eggs in the SO groups showed higher values than that in the control group when stored to 30 days at 4??P<0.05?.Storage time remarkably affected the MDA content in yolks,with a very significant increase in MDA content abserved with storege time.The MDA content in yolks very significant increased with dietary supplementation with SO?P<0.01?.With a high decrease in DHA content abserved among all the treatments with storege time?20 d⁵0 d?.Experiment 4:Effect of dietary choline and Schizochytrium oil on DHA enrichment in egg yolk and lipid metabolism in laying hens.Two hundred and eighty-eight 26-week-old laying hens were randomly divided into 4 groups of 6 replicates each and 12 birds in each replicate.Using a2×2 factorial experimental design,four isonotrogenous and isocaloric diets were supplemented with 0.05%choline(Choline_0.05),0.1%choline(Choline_0.1),0.05%choline+0.5%SO(Choline_0.05-SO_0.5),and 0.1%choline+0.5%SO(Choline_0.1+SO_0.5),respectively.All the birds were fed the basal diet in the control group for 7 days.The experimental period lasted 56 days.The results showed that compared with the no supplemtend with choline group,the dietary supplemented with choline 0.1%could increase the total phospholipids?PL?and phosphatidylcholines?PC?content in the yolks?P<0.01?.The interactions of choline and SO were significant on the content of PC in yolks?P<0.05?.Compared with the no supplemtend with SO group,the dietary supplemented with 0.5%SO could increase the n-3 PUFA and DHA content in the yolks?P<0.05?.The interactions of choline and SO were very significant on the content of DHA in yolks?P<0.01?.Dietary choline supplementation enhances the DHA enrichment in egg yolk.The SO_0.5 group extremely significant decreased the TC,TG,HDL-C,and LDL-L content in serum compared to the no supplemented with SO group?P<0.01?,while extremely significant increased in NEFA,VLDL-C and ox-LDL content?P<0.01?.Dietary 0.5%SO significantly increased contents of LPL and HL in serum?P<0.05?.Dietary supplemented with 0.1%choline could significantly increase the activities of CCT in liver compared to the dietary supplememented with 0.05%choline?P<0.01?.Experiment 5:Effect of dietary choline on synthetic pathway of DHA-PC base on lipidtemics.Two hundred and seventy laying hens of 28 weeks of age were allotted into 3 treatments groups with 6 replicates of 15 birds each.The control group was fed soybean meal-corn-SO basal diet,and2 of the experiment diets included 0.05%,and 0.15%of choline.All the birds were fed the basal diet(Choline_0.05)in the control group for 14 days.The experimental period lasted 28 days.The results showed that the DHA content was extremely significant increasing with the dietary choline increasing?P<0.01?.Compared with the control diet,the key synthesis enzyes on DHA-PC,that is ATGL and LPCAT,were increased in the Choline_0.15 diet?P<0.05?.We identified a total of 23 lipidclasses,829 lipid groups and 1240 lipid ions in egg yolk.Compare with the control diet,there is a significant increased on DHA-PC,DHA-LPC,and DHA-DG in the choline_0.15 diet?P<0.05?.The DHA only existed in the Sn-2 of PC and PE in the egg yolk.The weight ratio of PC?18:0/22:6?+HCOO is about 84%in the DHA-PC,while weight ratio of PE?16:0/22:6?+H is about 50%in the DHA-PC,and the PE?18:0/22:6?is 34%.The significant different lipids were PE?18:0/22:6?+H and PE?18:0/22:6?-H between Choline₀ and Choline_0.15groups?P<0.05?.The choline only increased the absolute content in lipidcalss when promoting DHA enrichment in egg yolk.In summary,the conclusion showed as follows:The DHA enrichment efficiency in egg yolk was significantly reduced with actual DHA intake.Compared with the SO group,the dietary supplementation with choline and SO increased the DHA and contents in yolk.The supplement of0.449%SO was optimal of its sources when dietary supplementation with 0.15%choline.There are two general reaction routes for the modification of DHA-TG to DHA-PC in laying hen:acyl exchange and interesterification.Choline can be used as diet additives to modify DHA-PC and DHA-LPC,and this is a feasible option that takes into consideration the need for PC to enrich egg yolks in DHA.The MDA content and DHA content in yolks showed minor changes when stored to20 days at 4?.