Effects And Mechanism Of Different Varieties And Level Of Rapeseed Meal And Full-fat Rapeseed On Laying Performance And Egg Quality In Laying Hens

3 experiments were designed to study the effects and mechanisms of different levels and varieties of rapeseed meal with different glucosinolates and erucic acid content on egg safety and health status in laying hens,and further to study the joint toxic action of glucosinolates and erucic acid in laying hens.Exp.1 Gls metabolites derived from RSM deposition and elimination in eggsA total of 900 thirty-week-old laying hens were randomly assigned to 6 dietary treatments with 10 replicates per treatment and 5 cages(3 hens)per replicate.The isoenergetic and isonitrogenous diets containing 0,5.88,11.76,17.64,23.52,and 29.40%RSM based on digestible amino acid,and 5-VOT content of diets was 0,23.55,68.71,83.16,88.49,and 94.25mg/kg,and SCN^-content of diets was 3.83,10.76,17.71,27.56,38.7,and49.85mg/kg.The study lasted for 16 weeks which contain 12 weeks accumulation phase and4 wk elimination phase.The results are as follows:1)For the whole experiment phase,11.76%RSM decreased ADFI and egg weight(P<0.05),and 17.64%RSM decreased egg production and increased FCR(P<0.01).17.64%RSM decreased DM and NEAA digestibility(P<0.01),and 29.4%RSM decreased AMEn,CP,and EAA digestibility(P<0.01).29.4%RSM increased eggshell strength at wk 4(P<0.05),and 17.64%RSM decreased albumen height at wk 4 and 29.4%RSM decreased Haugh unit at wk 12(P<0.05,P<0.01).RSM linearly increased egg yolk color at wk 4,12,and 1 to 12(P<0.05).After 4 weeks withdraw of RSM,the egg production performance and egg quality had no difference among 6 treatments(P>0.05).2)RSM linearly increased serum T3,T4,BUN content,and kidney and thyroid index at wk 12(P<0.05).After 4 weeks withdraw of RSM,the serum T3 and BUN content still linearly increased as the RSM increasing(P=0.01,P<0.01),but serum T4 content had no difference among 6 treatments(P=0.48).RSM linearly increased thyroid and kidney index(P=0.04,P<0.01).After 4 weeks withdraw of RSM,the thyroid and kidney index had no difference among 6 treatments(P>0.05).3)5-VOT recovery rate ranged from 81.28%to 103.28%with a RSD ranged from 0.75%to 5.17%.For the SCN^-detection,RSD values of precision is 0.81%.The RSD value of repeatability is 1.90%.The recovery rates are between 89.03%and 99.59%with 0.035%to 1.74%RSD.The 5-VOT accumulation was present in eggs only after hens the ingested RSM,and 5-VOT content in eggs was increased with 5-VOT intake at 3 phase(P<0.0001;P<0.0001;P<0.0001).Furthermore,the 5-VOT content in eggs was also linearly increased with increase of the feeding duration of dietary RSM feeding time in each group(P=0.001;P=0.06;P=0.017;P<0.0001;P=0.06).The 5-VOT content of eggs(Y,ng/g)was significantly correlated with dietary 5-VOT intake(X₂,?g/d.bird)and dietary 5-VOT feeding time(X₁,week):Y=54.94*X₁+0.51*X₂-430.34(P<0.01,R²=0.80).The SCN^-couldn't be detected in eggs of hens fed with control diet during accumulation phase.After a 4-week administration of RSM,the SCN^-content increased to 1.87,2.28,5.02,6.99,and8.32 mg/kg egg of hens fed with 5.88%to 29.40%RSM diet respectively,and the SCN^-concentration in eggs was linearly increased with dietary RSM intake at 3 phase(P<0.0001,P=0.004,P=0.0003).But the SCN^-Level of eggs didn't increase progressively and remained almost constant at different time points in 5.88%to 29.40%RSM diet group(P=0.05,P=0.22,P=0.69,P=0.38,P=0.35).The SCN^-Level of eggs(Y,mg/kg)was significantly correlated with dietary RSM intake(X₂,g/d.bird)and dietary RSM feeding time(X₁,week):Y=0.095*X₁+0.302*X₂-0.4211(P<0.01,R2=0.70).After 4 weeks withdrawal of RSM,the 5-VOT and SCN^-couldn't be detected in eggs.These results suggested that the amount of low glucosinolates and erucic acid RSM should not exceed 11.76%.The 5-VOT and SCN^-level of eggs were increased as the 5-VOT and SCN^-feeding time and feed intake.From the perspective of egg safety,the limit of OZT in hens compound feed should be lower than 59.98 mg/kg(as fed basis).After 4 weeks withdraw of RSM,the serum T4 content restored to normal level,but not serum T3 content.Exp.2 Effects different varieties and level of expeller rapeseed meal on laying performance,health status,and egg safety in laying hensAt 33 weeks of age,a total of 1080 laying hens were randomly divided into 9 treatment groups involving a control treatment without RSC(a corn-soybean diet)and a 2×4 factorial arrangement with 2 concentration of RSM concentrations(at 7 and 14%)from 4 varieties RSM varying in Gl and EA concentrations(DY5:74.66?mol/g(Gl),16.20%(EA);DY6:22.67?mol/g,0.7%,MB1:43.23?mol/g,3.5%,XH3:132.83?mol/g,44.60%).The trial lasted for 12 weeks containing 8 weeks accumulation phase and 4 weeks elimination phase.The results are as follows:1)Compared with control group,14%MB1 and XH3 RSC decreased egg production during wk 9 to 12(P<0.001),and RSC decreased egg weight during wk 1 to 8,and 9 to 12(P<0.05),and also decreased egg mass during wk1 to 8(P<0.01),but importantly,RSC variety had no effect on laying performance(P>0.05).7%and 14%RSC decreased ADFI during wk1 to 8(P<0.01),but RSC variety had no effect on ADFI during each phase(P>0.05).RSC variety and level had an interaction effect on FCR during wk 9 to 12(P=0.04).After 4 weeks withdraw of RSC,the laying performance had no difference among 9 groups(P>0.05).2)Compared with control group,7%MB1 and DY5 RSC decreased AMEn at wk 8,and 7%DY5,14%MB1,and 14%DY5 decreased DM digestibility(P<0.01),but 7%and14%RSC increased crude fat digestibility(P<0.01).14%RSM had a higher AME than 7%RSM(P=0.01),and XH3 variety had a lower crude fat than DY6 variety(P<0.01).Crude protein of XH3 variety was 6.25%lower than DY6 variety.RSC addition decreased villi height and crypt depth of duodenum at wk 8 compared with control group(P<0.001),14%RSC had a higher crypt depth of duodenum than 7%RSM(P=0.009).DY6 variety had a higher villi height and villi height to crypt depth ratio than DY,MB1,and XH3 variety(P<0.01),and RSM variety and level had an interaction effect on villi height and villi height to crypt ratio(P<0.01).XH3 variety had a higher crypt depth than DY5,MB1,and DY6(P<0.01).compared with control group,RSC decreased villi height and crypt depth of jejunum at wk 8(P<0.001),14%RSM had a higher crypt depth and villi height to crypt depth ratio of jejunum than 7%RSM(P<0.01).DY6 variety had a higher villi height of jejunum than MB1 variety,and XH3 had the lowest villi height of jejunum(P<0.01).3)Compared with control group,RSC decreased serum LDL-C content,and increased serum UREA level at wk 8(P=0.02,P=0.02),and 14%RSC had a higher ALT and TC content than 7%RSM(P=0.002,P=0.035).XH3 variety had a higher serum UREA content than DY6 variety(P=0.047).RSC had a lower serum E2 content than control group(P<0.001),and DY6 variety had a higher serum E2 content than MB1,DY5,and XH3variety(P=0.01).Serum TMAO content of 14%XH3 RSC was 4 times than that of Control group.4)Compared with control group,RSC increased red O oil density,TC,and LDL-C content in liver at wk 8(P=0.004,P=0.03,P=0.03),and decreased TBA level in liver at wk8(P<0.001).14%RSC had a higher LDL-C content in liver than 7%RSM(P=0.04),and14%RSC had a lower TBA content in liver than 7%RSC(P<0.001).XH3 variety had the lowest TBA Level in liver(P<0.001).RSC addition decreased the mRNA abundance of LXR-?(P<0.001).5)Compared with control group,14%RSC increased the ratio of apoptotic liver cells at wk 8 compared with control and 7%RSC group(P=0.03,P=0.001).RSC decreased mRNA abundance of FMO₃,cas-9,and StAR(P<0.001,P=0.02,P=0.02),and increased mRNA abundance of GhR(P<0.001).14%RSC had a lower mRNA abundance of IL-6 and Bcl-2 than 7%RSC(P<0.001).XH3 and DY5 varieties had a lower mRNA abundance of GhR than DY6 and MB1 varieties(P=0.04),and DY5 variety had a lower mRNA abundance of cas-8 than other 3 varieties of RSM(P=0.05).RSC decreased mRNA abundance of Bcl-2 and IGF-1R of ovary at wk 8(P=0.02,P<0.001),and increased mRNA abundance of FshR(P<0.001),and DY6 variety had a higher mRNA abundance of IGF-1R than other 3 varieties of RSM(P<0.001),and meanwhile RSC variety and level had an interaction effect on mRNA abundance of IGF-1R(P=0.02).6)Compared with control group,14%RSC decreased albumen height at wk 2,4,and8(P<0.05),and 7%and 14%RSC increased egg yolk color at wk 2 and 4(P<0.001),while only 14%RSC increased yolk color at wk 6 and 8(P<0.001).DY6 variety had a higher albumen height than XH3 variety at wk 8(P=0.012).DY6 variety had a higher egg yolk color than other 3 varieties of RSC at wk 6 and 8(P<0.01),and RSC variety and level and an interaction effect of yolk color(P<0.01).14%XH3 RSC decreased Haugh unit at wk 2and 4(P<0.05).DY6 variety had a higher Haugh unit than DY5 and XH3 variety at wk 6and 8(P=0.001),and RSC variety and level had an interaction effect on Haugh unit(P=0.015).After 4 weeks withdraw of RSC,there was no difference on egg quality between control and RSC group(P>0.05).7)Compared with control group,RSC decreased SFA ratio in egg yolk lipids at wk 8(P=0.01),and increased PUFA ratio(P=0.04).XH3 variety had a higher C_18:1n9t8:1n9t and C_22:1n9content in egg yolk lipids than DY6 and MB1 variety(P=0.048,P=0.008).DY5 variety had a higher His content in egg yolk than XH3 variety at wk 8(P=0.04),and DY5 variety had a higher Arg content in egg yolk than DY6 and MB1 variety at wk 8(P=0.001).DY6 and XH3variety had a higher Thr content in egg white than MB1 variety(P=0.048),and DY5 variety had a higher His content than MB1 variety(P=0.02).XH3 and DY5 had a higher Arg content than MB1 variety(P=0.04).RSC decreased SOD content of egg yolk(P=0.02).DY6 variety had a higher egg white gel strength and egg flavor quality than DY5 or MB1,and XH3variety(P=0.001,P<0.001).The 5-VOT and SCN^-Level in eggs were increased as the dietary Gls Level increasing,and XH3 variety had the highest 5-VOT and SCN^-Level of eggs among the 4 varieties of RSC(P<0.001),RSC variety and level had an interaction effect on these 2 toxins deposition in eggs(P<0.001).After 4 weeks withdraw of RSC,these 2toxins couldn't be detected in eggs.RSC decreased FMO₃ activity of liver at wk 8 compared with control group(P=0.029),and also,RSC increased TMA content in egg yolk(P<0.001),and XH3 variety had a higher TMA content than other 3 varieties of RSC.8)The plot of beta diversity index showed significant separate clustering of cecum microbiota of the control and RSC group(P=0.014).At the phylum level,RSC had a trend to increase abundance of Cyanobacteria and Saccharibacteria(P=0.08,P=0.07),and decreased Ignavibacteriae,Chloroflexi,and Planctomycetes(P=0.05).At the genus level,there are 11 different microbes between control and RSC group.At the phylum level,the bacterial abundance of Tenericutes and Verrucomicrobia were negatively correlated with 5-VOT content in eggs(P=0.04),and SCN^-content of eggs was negatively correlated with the bacterial abundance of Firmicutes and Tenericutes(P=0.04).Dietary Gls,SCN^-,and sinapine content and EA content explained 33.16%and 7.84%of the total variance,and interaction effect contributed 59%of the total variance.These results suggested that 14%XH3 and MB1 RSC decreased egg laying rate and egg mass,while 4 varieties of RSC could decrease ADFI and egg weight.RSC variety had no effect on egg production performance.The lower nutrients digestibility,lower villi height of intestinal,liver damage,follicles apoptosis,and different microbial diversity might be correlated with the lower laying performance of RSC group.The bacterial abundances of predominant phyla were significantly correlated with 5-VOT and SCN-deposition in eggs.Eggs of hens fed with 7%DY6 RSM at wk 8 was safe for infant based on the 5-VOT and SCN^-limit in food.Exp.3 Effects of different varieties of full-fat rapeseed on laying performance,health status,and egg safety in laying hensA total of 600 33 weeks of age laying hens were randomly assigned to 5 dietary treatments with 8 replicates per treatment and 5 cages(3 hens)per replicate.The isoenergetic and isonitrogenous diets containing 0 and 11.5%rapeseed(RS)containing 4 varieties of RS based on digestible amino acid.The study lasted for 12 weeks with 8 weeks accumulation phase and 4 weeks elimination phase.The results are as follows:1)Compared with control group,11.5%RS decreased laying performance containing ADFI,egg production,egg weight,egg mass,and FCR during each phase(P<0.01),and XH3 variety exhibited lower egg production during wk1 to 8 than DY6 RS(P<0.01).XH3RS and DY5 had a lower egg weight and egg mass during wk1 to 8 than DY6 RS(P<0.001).After 4 weeks of withdraw of RS,RS still exhibited lower laying performance compared with control group(P<0.05),but there was no difference among 4 varieties of RS(P>0.05).2)Compared with control group,11.5%RS decreased AME,DM,CP,and CF digestibility at wk 8(P<0.05),and DY6 variety had a higher CF digestibility than DY5 and MB1 varieties,DY5 variety exhibited higher CF digestibility.11.5%RS exhibited lower duodenum VH,IWT,and V/C(P<0.01),and XH3 variety showed a higher CD than DY6RS.11.5%RS decreased jejunum VH,CD,and V/C(P<0.05),and XH3 RS exhibited a higher CD than MB1 and DY6.3)Compared with control group,11.5%RS decreased serum LDL-C content at wk 8(P=0.001),DY6 RS exhibited a higher serum LDL-C content than MB1 and XH3 RS(P=0.0001).11.5%RS lowered serum E2 content and increased serum TMAO content(P<0.001,P=0.01),and XH3 and DY5 had a lower TMAO content than MB1 and DY6 RS.RS increased liver LDL-C content and decreased liver TBA content at wk 8(P<0.0001),and XH3 exhibited a lower liver TBA than DY6.RS up-regulated SREBP2 expression(P=0.03),and XH3 and DY5 had a higher SREBP1 expression than DY6(P=0.01).4)Compared with control group,11.5%RS decreased abdominal fat index and the number of the largest ovary follicle at wk 8(P<0.01),and increased thyroid index(P=0.007),and XH3 had a higher thyroid index than MB1 and DY6.DY5 had a higher kidney index than DY6(P=0.03).11.5%RS increased the liver cell apoptosis rate(P=0.0034)with down-regulating of the mRNA abundance of FMO₃,cas-9,Bcl-2,ER2?StAR,and IGF-1R(P<0.05),and impressively,the mRNA abundance of IGF-IR in RS group is 19 times that of control group,and DY6 RS had a higher IGF-1R mRNA abundance than DY5 and XH3RS(P<0.0001).5)MB1,DY5,and XH3 RS had a lower L*value than control group at wk 4,and DY6had a higher L*value than XH3 at wk 4(P=0.02).XH3 variety exhibited a higher a*of eggshell MB1 and DY5 at wk 8(P<0.001).XH3 variety lowered albumen height,and lowered Haugh unit compared with DY6 variety at wk 6(P=0.009,P=0.02).11.5%RS decreased SFA ratio in yolk lipids compared with control group at wk 8(P<0.001),and increased UFA ratio containing C₁₈:_1n9c,C₂₀:_1n9,and C₂₂:_1n9 in yolk lipids(P<0.05).XH3variety exhibited a higher C₂₂:_1n9n9 content than MB1 and DY6 variety(P<0.001).After 4weeks withdraw of RS,there was no difference on egg quality among 5 treatments(P>0.05).6)5-VOT and SCN^-couldn't be detected in eggs at wk 8,and the effects of different varieties of RS on the deposition of 5-VOT and SCN^-in eggs are as follows,DY6:469.21ng/g and 8.3mg/kg,MB1:467.85ng/g and 9.2mg/kg,DY5:1252.1ng/g and10.33mg/kg,XH3:3210.93ng/g and 11mg/kg.compared with control diet,11.5%RS had a trend to decrease liver FMO₃ activity(P=0.088),and RS variety had no effect on it.Accordingly,11.5%RS exhibited higher TMA content of egg yolk than control diet(P<0.0001),and TMA content of egg yolk had no difference among 4 varieties of RS(P>0.05).After 4 weeks withdraw of RS,13.56 ng/g 5-VOT of eggs was detected in hens fed with 11.5%DY6 RS,and the 5-VOT Level of eggs of hens fed with DY5 or XH3 was4.87 and 7.39ng/g respectively,while SCN^-couldn't be detected in eggs.7)The plot of beta diversity index showed significant separate clustering of cecum microbiota of control and RS group(P=0.001).At the phylum level,RS exhibited higher abundance of Bacteroidetes than control group(P=0.02),and decreased abundance of Firmicutes,Actinobacteria,Tenericutes,Deferribacteres,Spirochaetes,and Planctomycetes(P<0.05).At the genus level,there are 19 different microbes between control and RS group.Dietary Gls,SCN^-,and sinapine content and EA content explained 48.46%and 26.50%of the total variance,and interactions between the 2 environmental factors contributed 25.04%of the total variance.These results suggested that dietary RS had a great negative impact on laying hens,and high Gls and EA RS had a lower laying performance,egg quality,nutrient digestibility than that of low Gls and EA RS.Heat processing of RS could weaken the negative impact of Gls and EA.Eggs of hens fed with 11.5%DY6,MB1,DY5,and XH3 RS at wk 8 maybe not safe for infant based on the 5-VOT limit in food,and 11.5%DY6 and MB1 are safe for human based on the SCN^-limit in food.Most importantly,4 weeks withdraw of 11.5%RS maybe not enough for restoring laying performance and 5-VOT and SCN^-content of eggs back to normal levels.In summary,based on egg production performance,the use of low Gls and EA RSM should not exceed 11.76%(OZT<119.95 mg/kg).The 5-VOT and SCN^-deposition in eggs increased with the increase of dietary 5-VOT and SCN^-intake and feeding time,and the phylum Tenericutes and Verrucomicrobia were negatively correlated with 5-VOT content in eggs,and SCN^-content of eggs was negatively correlated with the phylum Firmicutes and Tenericutes.Based on the egg safety,we recommend that the limit of OZT in hens compound feeds should be lower than 59.98mg/kg air-dried substance,And the feeding time should not exceed 4 weeks.After 4 weeks of withdrawn of RSM,5-VOT and SCN^-could not be detected in eggs,and egg performance and egg quality had recovered.While eggs from hens fed with RS still detected 5-VOT and SCN^-,and egg production had not recovered.RS and its by-products could induce TC and LDL-C deposition in liver,and we speculated that sinapine increased serum TMAO content,and further down-regulating the mRNA expression of LXR-?and CYP7A1,and finally inhibited the conversion of liver TC to TBA;Thirdly,up-regulating of mRNA abundance of SREBP2 increased TC synthesis the in liver.Heat processing of RS can reduce 5-VOT and SCN-deposition in eggs.