Effects And Mechanism Of Rapeseed Processed Products With Different Glucosinolate And Erucic Acid Contents On Laying Performance And Egg Quality Of Laying Ducks

Four experiments were designed to study the effects of different varieties of rapeseed cake(RSC),rapeseed oil(RSO),5-vinyl-1,3-oxazolidine-2-thione(5-VOT)and erucic acid(EA)on laying performance,egg quality and health status of laying ducks,and further to explore the action mechanism of RSC on the performance and egg quality of laying ducks.Exp.1 Effects of RSC with different glucosinolate and EA content on performance,egg quality and health of laying ducks.This experiment was conducted to investigate the effect of RSC with different content of glucosinolates(Gls)and EA on performance,egg quality and health of laying ducks.A total of 576 twenty-eight-wks-old laying ducks were randomly allocated to 4 treatments.Each treatment had 8 replicates of 18 laying ducks raised in 6 adjacent cages with 3 laying ducks per cage.The control was corn soybean meal diet without RSC.Three varieties of RSC varying in Gls concentrations were supplemented to the base diet at 10%by substituting soybean meal to formulate the three RSC diets.The experiment lasted 12 wks.The results were as follows:1)Diets with 10%RSC decreased average egg weight(P<0.05)and feed intake(P=0.07)compared with the control diet.RSC increased color value(P<0.05)and crude protein(CP)content(P<0.05)of yolk compared with the control diet.RSC decreased monounsaturated fatty acids(MUFA)(P<0.01)and increased polyunsaturated fatty acids(PUFA)(P<0.01)of yolk.RSC increased deposition of trimethylamine(TMA)and5-VOT in yolk(P<0.01);moreover,the double-high RSC increased deposition of TMA(P<0.01)and 5-VOT in yolk(P<0.01)compared with the other two double-low RSC varieties.2)Diets with 10%RSC significantly increased liver antioxidant enzyme activity(P<0.05)and thyroid index(P<0.01),and decreased liver cholesterol content(P<0.05).Double-high RSC significantly decreased the villus height of duodenum and the crypt depth of ileum(P<0.05),and significantly increased the number of apoptotic cells in liver and thyroid(P<0.05).3)RSC significantly affected the cecal microbial composition of laying ducks.The Synergistetes,Synergistes and Clostridium abundance was significantly higher than control group(P=0.011,P=0.04 and P=0.005),while Sphingomonas,Selenomonas and muribaculum abundance were significantly lower than control group(P=0.013,P=0.049and P=0.013).The Gls,EA,Isothiocyanate(ITC)and 5-VOT content of the diets were negatively correlated with Firmicutes(P<0.05)and positively correlated with Actinobacteria(P<0.05),while the Gls,EA,ITC and 5-VOT contents of the diet were negatively correlated with anaerobiospirillum(P<0.05)and positively correlated with Clostridium(P<0.01);The sinapine content of the diet was positively correlated with Actinobacteria,Ruminococcus and Clostridium(P<0.05).These results suggested that laying duck diet with 10%of the three varieties of RSC affected the thyroid function,cecal microbial composition and liver lipid metabolism of laying ducks,moreover,the adverse impacts of double-high RSC on the liver and thyroid of laying ducks were higher than double-low RSC.Exp.2 Effect of double-high RSC levels on performance and egg quality of laying ducks.This experiment was conducted to investgate the effects of double-high RSC levels on the egg production performance and egg quality of laying ducks.A total of 420sixty-one-wks-old laying ducks were randomly allocated to 6 treatments.The control group was fed corn soybean meal diet,RSC diets were added with 6%double-low RSC DY6 or 2%,4%,6%and 8%double-high RSC H405 respectively.Each treatment had 5replicates with 14 laying ducks in each replicate.The trial lasted for 12 weeks,and the results were as follows:1)Compared with control group,6%double-low RSC DY6 and 2%,4%and 6%double-high RSC did not significantly affect laying performance of ducks,but 8%double-high RSC H405 depressed the egg production rate,daily egg production and FCR significantly.2)The deposition of TMA and 5-VOT in yolk showed a linear change with the level of double-high RSC H405 in the diets.The regression equation between the yolk TMA content(Y,mg/kg)and the diets sinapine content(X,%)was Y=0.019*X+3.274(R~2=0.71,P<0.001);The regression equation between yolk 5-VOT content(Y,μg/kg)and the diet 5-VOT content(X,%)was Y=9.031*X+47.121(R~2=0.88,P<0.001).3)The deposition of TMA and 5-VOT in yolk showed a quadratic curve change with the feeding time of the double-high RSC.The regression equation between yolk TMA content(Y,mg/kg)and feeding time(X,d)was Y=-0.076*X~2+2.736*X-1.228(R~2=0.70,P<0.001),the regression equation between yolk 5-VOT content(Y,μg/kg)and feeding time(X,d)was Y=-2.618*X~2+106.34*X+33.273(R~2=0.72,P<0.001)。These results suggested that laying duck diet with 6%double-low RSC had no significant effect on laying performance,while 8%double-high RSC significantly depressed the laying performance.The optimal level of double-high RSC H405 in laying duck diets was 6%,4%and 2%when considering the laying performance,egg safety and egg flavor as the marker respectively.Exp3.Effects rapeseed oil with different EA content on laying performance,egg quality and health of laying ducksThis experiment was conducted to evaluate the effects and mechanism of rapeseed oil(RSO)with different EA content on laying performance,egg quality and health of laying ducks.A total of 216 thirty-six-wks-old laying ducks were randomly allocated to three treatments,each treatment had 5 replicates with 14 laying ducks in each replicate.The control diet was formulated with 3.7%soybean oil,and 3.7%low erucic acid RSO DY6 or high erucic acid RSO H405 was supplemented to the basic diet by substituting soybean oil to formulate RSO diets.This trial lasted 12 wks,and the results were as follows:1)Compared with the control group,low erucic acid RSO DY6 resulted in poor FCR(P<0.01),high erucic acid RSO H405 decreased egg weight,egg mass and FCR(P<0.05).High erucic acid RSO H405 significantly reduced egg weight(P<0.01)compared with low erucic acid RSO DY6.2)Compared with control and low erucic acid RSO DY5 group,high erucic acid RSO H405 decreased the egg weight and yolk ratio(P<0.01).,while increased the albumen ratio and yolk color of eggs(P<0.01).3)Compared with the control group,both low erucic acid RSO and high erucic acid RSO significantly increased MUFA,UFA,EA content and USFA/SFA ratio(P<0.05),decreased PUFA,SFA content andω-6/ω-3 ratio of yolks(P<0.05).Compared with low erucic acid RSO DY6,high erucic acid RSO significantly increased C16:0,C16:1,C20:1,C20:2,C20:5 and C22:1(EA)content(P<0.01),and significantly decreased C18:0,C18:1 content andω-6/ω-3 ratio of yolks(P<0.01).4)Compared with the control group,low erucic acid RSO significantly increased serum TC level(P<0.05),and high erucic acid RSO significantly increased blood biochemical parameters including MCV,MCH,ALP,LH and TC level.High erucic acid RSO promoted follicular atresia and increased the number of atretic follicles compared with control and low erucic acid RSO group(P<0.05).5)Fusobacterium in the high erucic acid rapeseed oil group was significantly lower than control group(P=0.043),while Shigella was significantly higher than control group(P=0.027).Megamonas in the low erucic acid rapeseed oil group was significantly higher than control group(P=0.043).Diet EA level was significantly negatively correlated with Deferrobacteria and Fusobacterium(P<0.05).These results above suggested that 3.7%high erucic acid or low erucic acid RSO depressed the performance of laying ducks compared with soybean oil.Moreover,high erucic acid RSO had greater negative effects on performance and health of laying ducks by affecting gut microbiota,lipid metabolism and ovarian function.Exp.4 Effect of 5-VOT and EA supplement alone or combination on the performance and health of laying ducks.This experiment was conducted to evaluate the effect and mechanism of 5-VOT and EA supplement alone or in combination on the performance and health of laying ducks.A total of 120 fifty-five-wks-old laying ducks were randomly allocated to four treatments.Each treatment had 30 replicates with one laying duck per replicate raised in a cage.The experiment lasted 8 wks.Laying ducks were expoured to corresponding diets during the first four weeks,then were fed the same base diets during the last four weeks.The results were as follows:1)Compared with the control or EA group,5-VOT alone or combined with EA significantly depressed the laying rate,feed intake,egg production and FCR.2)The 5-VOT deposition in egg yolk was 3978μg/kg and 4355μg/kg after exposure to 5-VOT diet and 5-VOT plus EA dite for 4 weeks,the 5-VOT residual in egg yolk was24.8μg/kg and 24.7μg/kg after 2 weeks recovery accordingly,and 5-VOT was completly eliminated after 4 weeks recovery.3)Diet supplemented with 5-VOT alone or combimed with EA significantly increased the thyroid index of laying ducks(P<0.001),while the thyroid index was recoveried after4 weeks recovery.5-VOT significantly increased the TG and MDA content of liver(P<0.05),while EA significantly increased Caspase-9 gene expression of liver(P<0.05).Diets supplemented with 5-VOT alone or combined with EA increased Caspase-9 gene expression of ovary(P<0.05)and decreased the proportion of grade follicles(P<0.05).These results above suggested that 140 mg/kg 5-VOT depressed the feed intake of laying ducks,resulted in goiter and upregulated caspase-9 gene expression in ovary,finally depressed the health and performance of laying ducks.Diet supplemented with 0.42%EA had no significant impact on the performance of laying ducks,thus the combination of EA and 5-VOT did not aggravate the negative effects of 5-VOT on the performance and health of laying ducks.In summary,laying ducks diet containing 10%RSC with different content of glucosinolates(Gls)depressed the performance and health of laying ducks by increasing the apoptosis of liver and thyroid,moreover,the adverse impacts of double-high RSC on laying ducks was greater than double-low RSC.RSC resulted in TMA and 5-VOT deposition in yolk,which was linear correlation with RSC level and quadratic correlation with exposure duration.High erucic acid or low erucic acid RSO depressed the performance of laying ducks compared with soybean oil.Moreover,high erucic acid RSO had greater negative effects on performance and health of laying ducks by affecting gut microbiota,lipid metabolism and ovarian function.Diet supplemented with 140 mg/kg5-VOT depressed the feed intake of laying ducks,resulted in goiter and upregulated caspase-9 gene expression in ovary,finally depressed the health and performance of laying ducks.The optimum level of double-high RSC in the laying duck diet was 6%,4%and 2%when considering the production performance,egg safety and egg flavor as the indicator respectively,therefore,the 5-VOT limitation in laying duck diet was 84 mg/kg,56 mg/kg and 28 mg/kg when considering the laying performance,5-VOT residual and TMA deposition as the indicator respectively.