Effect Of Different Varieties Of Rapeseed Oil On Production Performance,Lipid Metabolism And Egg Quality Of Laying Hens

The aim of this study was to investigate the effect of different varieties of rapeseed oil on production performance,lipid metabolism and egg quality of laying hens.It provided theoretical support for the rational use of different varieties of rapeseed oil in layer diets and provided scientific guidance for safe production of eggs.A total of 1080 Lohman laying hens(33-wk-old)were assigned to 9 dietary treatments in a 4×2+1 completely randomized design,with 8 replicate per treatment.The 9 treatments included 1 diet without rapeseed oil or diets containing four different rapeseed oil varieties(HE,ME,MLE,LE)at two inclusion levels(2% and 4%)for 12 wk.The results showed:1)The erucic acid content in the diet showed regular changes with the erucic acid content and rapeseed oil level.The erucic acid content in the 4% HE group was 37.62%.No erucic acid was detected in the 2% LE diet.2)Compared with the control group,rapeseed oil treatment significantly reduced the egg production(P < 0.05)at 9-12 wk and 1-12 wk,egg weight,ADFI and FCR(P < 0.05).The egg weight of the MLE rapeseed oil group was significantly higher than(P < 0.05)ME rapeseed oil group(all stages)or HE rapeseed oil group(during 5-8wk,9-12 wk or 1-12wk).The feed intake of the MLE rapeseed oil group was significantly higher than(P < 0.01)HE and LE rapeseed oil group.The FCR showed a certain trend,which showed HE rapeseed oil group was higher(P < 0.1)than other three rapeseed oil groups(1-4wk),ME group had a higher(P < 0.1)FCR than other three rapeseed oil groups(9-12 wk and 1-12wk).Compared with 2% rapeseed oil,4% rapeseed oil significantly reduced(P < 0.01)egg weight at 1-4 wk,9-12 wk and 1-12 wk,ADFI at each stage and FCR at 1-4 wk.3)Compared with the control group,rapeseed oil significantly increased(P < 0.01)the apparent utilization of crude fat,crude protein,and the apparent metabolizable energy of the diet.The utilization of dry matter and crude fat in ME rapeseed oil group was the highest,which was significantly higher than that of(P < 0.01)LE rapeseed oil diet;the crude fat utilization of LE rapeseed oil group diet was also significantly lower than the other three rapeseed oil diets;the apparent metabolizable energy of the MLE rapeseed oil group diet was the highest,which was significantly higher than(P = 0.03)the other three rapeseed oil diets.Compared with 2% rapeseed oil diets,4% rapeseed oil significantly reduced dietary dry matter(P < 0.01)and crude protein(P = 0.01)utilization,but significantly increased crude fat utilization(P<0.01)and apparent metabolizable energy(P=0.03).Rapeseed oil varieties and levels had significant(P<0.01)interactions on dry matter,crude protein utilization,and apparent metabolizable energy.4)Compared with the control,4% ME rapeseed oil significantly increased(P < 0.01)albumen height and Haugh unit at 4wk;2%,4% HE and ME rapeseed oil group,4% MLE and LE rapeseed oil group significantly decreased(P < 0.01)yolk color at 8wk;albumen height and Haugh unit was significantly increased(P < 0.01)but yolk color was decreased(P < 0.01)at 12 wk.After 7-day storage,albumen height and Haugh unit was increased compared with control,the difference between 4% ME rapeseed oil group and control reached a significant level.After 14-day storage,The yolk color was decreased and the Haugh unit was increased compared with control,the difference between 2% HE,4% ME rapeseed oil group and control group reached a significant level.The albumen height and Haugh unit of the HE rapeseed oil group were significantly lower(P < 0.01)ME and MLE rapeseed oil group at 4wk.The yolk ratio of ME rapeseed oil group was significantly higher than(P = 0.02)MLE and LE rapeseed oil group at 8wk.The HE rapeseed oil has the highest yolk color and was significantly different from LE rapeseed oil group after 7-day or 14-day storage.Compared with 2% rapeseed oil,4% rapeseed oil significantly increased(P = 0.04)the eggshell color b value at 4wk,decreased(P < 0.01)the egg yolk ratio at 8wk and after 7-day and 14-day storage,decreased(P < 0.01)the yolk color and egg yolk ratio and increased(P < 0.01)the egg white ratio at 12 wk.The yolk cholesterol content in eggs fed with MLE was significantly lower(P = 0.03)than that of HE and ME rapeseed oil group.Rapeseed oil has an effect on the content of various fatty acids in the egg yolk.The content of erucic acid in HE rapeseed oil group was the highest,followed by ME rapeseed oil group.There was a significant difference between the two groups,and they were all significantly higher than those in the MLE and LE rapeseed oil groups.Compared with 2% rapeseed oil,4% rapeseed oil significantly increased(P < 0.01)the content of linoleic acid,?-linolenic acid,erucic acid and PUFA in egg yolk.Compared with the control group,rapeseed oil decreased(P < 0.01)egg yolk SOD and albumen SOD.Compared with the four varieties of rapeseed oil,the egg yolk MDA was highest in the HE group.Compared with 2% rapeseed oil,4% rapeseed oil significantly decreased(P = 0.03)yolk SOD.The albumen color of the MLE group was significantly higher(P = 0.02)than the HE group.The albumen taste of the LE group was significantly higher(P = 0.05)than the HE group.The yolk texture of the ME group was significantly higher than(P = 0.03)the HE group.5)Compared with the control group,rapeseed oil treatment decreased TG(P < 0.01)and increased HDL-C(P = 0.02).HE group had higher TG(P < 0.01),TC(P = 0.04)than MLE and LE group.Compared with 2% rapeseed oil,4% rapeseed oil significantly reduced the liver TG content(P <0.01)and the relative liver weight(P = 0.04).The hepatic total fat(P = 0.01),TG(P <0.01),and TC(P <0.01)in the HE group were higher than those of LE group,and the varieties and levels of rapeseed oil had significant interactions on liver TG content(P < 0.01).Layers fed HE significantly increased(P < 0.01)the expression of LPL in liver than that of layers fed with MLE.The expression of ACC was significantly higher(P <0.01)in layers fed with MLE when compared with layers fed with HE and LE.The expression of PPAR?,apoB-100,and apoB-VLDL were significantly higher(P < 0.01)in layers fed with LE than those fed with other varieties.Taken together,adding rapeseed oil to the diet decreased the production performance of laying hens.Layers showed more undesirable production performance when fed with HE and ME rapeseed oil with high erucic acid content.Compared with 2% rapeseed oil,4% rapeseed oil showed more undesirable production performance.Compared with the high erucic acid rapeseed oil group,the low erucic acid rapeseed oil increased the serum lipid content and the fat content in liver,which may be related to the upregulation of the apolipoprotein synthesis gene expression of apoB-100,apoBVLDL-II thus increased fat transport.The PUFA content of egg yolk in the HE and ME groups was lower than that in the MLE and LE groups.The deposition of erucic acid in the egg yolk was highly correlated with the erucic acid content in the rapeseed oil.Compared with the MLE and LE groups,the MDA content of yolk was higher than the HE and ME groups,indicating that erucic acid increased egg lipid peroxidation level.