Effects Of Enzyme-Treated Soy Protein On Laying Performance,Body Health And Egg Quality Of Laying Hens

This experiment was conducted to investigate effects of different nutrients levels diet supplemented with Enzyme-treated Soy Protein?ETSP?on laying performance,egg quality,nutrient apparent availability and body health of laying hens.A 3�2 factorial design with 3nutrients levels:?ME:2680 kcal/kg,CP:15.5%;ME:2630Kcal/kg,CP:15%;ME:2580Kcal/kg,CP:14.5%?and two ETSP levels?0%and 0.5%?.High nutrients levels diet without ETSP was a positive control?PC?treatment,lower nutrients levels diets were two negative control?NC1 and NC2?treatments.A total of 1200 Lohmann pink laying hens?52-weeks-old?were randomly divided into 6 treatments with 10 replicates per treatment and 20 laying hens per replicate groups.The experiment lasted for 12 weeks.The results showed as follows:1)With the decrease of nutrient levels in diet,average laying rate of laying hens in 5-8weeks significantly increased,1-4weeks?P=0.08?and 1-12weeks?P=0.07?had a decreasing tendency.The ratio of feed to egg of PC significantly lower than group NC1 and NC2 in 1-4weeks,in 5-8weeks?P=0.05?and 1-12weeks?P=0.06?had an increasing tendency?P=0.06?.With the ETSP supplemented,the ratio of feed to egg had a decreasing tendency?P=0.05?,and qualified egg rate was significantly increased?P<0.05?.Moreover,the EE apparent availability of PC is significantly higher than group NC1 and NC2;With the increase of ETSP supplemented levels,The egg-laying rate in the additive group was higher than that in the non-additive group,but did not reach a significant level.The ratio of feed to egg had a decreasing tendency?P=0.05?in 1-12weeks,and the ETSP supplementation and qualified egg rate was significantly increased?P<0.05?.Furthermore,The interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on apparent availability of total energy of laying hens?P<0.05?,PC nutrient levels diet supplemented with ETSP significantly rised apparent availability of total energy.2)When dietary nutrition level was reduced,the L_*value of eggshell decreased significantly?P<0.01?and a_*value and b_*value increased significantly?P<0.01?in the fourth week,but no significant influence was found on the internal quality of eggs?eggshell strength,albumen height,Haugh unit,yolk color and yolk index?.At the eighth week,the a_*value of shell color was significantly increased.At the twelfth week,the score of yolk color decreased?P=0.09?.The supplementation of ETSP significantly reduced the L_*value of eggshell color at the fourth week?P<0.05?,significantly increased the a_*value of eggshell color and yolk index the eighth week?P<0.05?,and significantly increased the yolk color the twelfth week?P<0.01?.The interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on albumen height and Haugh unit at the twelfth week?P<0.05?,NC1 nutrient levels diet supplemented with ETSP significantly increased albumen height and Haugh unit.The supplementation of ETSP significantly decreaced mass loss rate of eggs which storage for 30 and 45 days.The interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on albumen height and Haugh unit after storage for 30 days?P<0.05?,NC2 nutrient levels diet supplemented with ETSP significantly increased albumen height and Haugh unit.3)With the decrease of nutrient levels in diet,the content of serum UA and T4 increased significantly?P<0.05?,TP level of laying hens increased,but did not reach the significant level.The interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on srrum COR contain?P<0.05?,PC nutrient levels diet supplemented with ETSP significantly decreased the contain of srrum COR.4)Neither dietary nutrient level nor ETSP had significant effect on liver and spleen indexes of laying hens.In lower nutrition level in diet,the contents of IgA?P<0.05?,IgM?P<0.01?and lysozyme?P<0.05?decreased significantly,and NC2 group was significantly lower than that of PC and NC1 group.The contents of serum IgA?P<0.05?,IgG?P<0.05?,IgM?P<0.05?and lysozyme?P<0.01?were significantly increased by using ETSP.The interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on IgM content?P<0.05?,which was reflected in that at the level of NC2,ETSP significantly increased the IgM content.5)MDA content in laying hens liver at nutrition level of NC2 was significantly higher than PC and NC1?P<0.05?.With the decrease of nutrition level in diet,SOD activity tended to decrease?P=0.09?,but had no significant effect on antioxidant indexes of ovary and magnum of fallopian tube.With the supplementation of ETSP the liver MDA content decreased significantly,and the interaction of nutrient levels in diet and ETSP supplemented levels had significant effects on the liver MDA content and the SOD activity of magnum,ETSP can significantly reduce liver MDA content in NC2,significantly increace the SOD activity of magnum.6)With the decrease of nutrient levels in diet,crypt depth of jejunum had an increasing tendency?P=0.06?,the ratio of villous height to crypt depth?V/C?of jejunum was significantly decreased?P<0.05?.However,the relative expression levels of jejunum PepT1,B0AT,EAAT3 and CAT1 mRNA and caecum microflora in laying hens were not significantly affected.With the increase of ETSP supplemented levels,villous height of duodenum had an increasing tendency?P=0.09?,V/C and the activity of trypsin of duodenum was significantly increased?P<0.05?.The relative expression levels of jejunum PepT1?P<0.05?and B₀AT mRNA?P<0.01?were significantly increased.At the same time,the quantity of lactobacillus caecum in laying hens was on the rise?P=0.06?.In conclusion,lower dietary nutrition level will affect the laying performance and egg quality of laying hens,reduce the nutrient apparent availability,and have a certain negative impact on immune function and intestinal health.Diets supplemented with ETSP can improve laying performance and egg quality of laying hens by increase apparent availabilities of CP and EE in diet,improving immunity,antioxidant function and intestinal health of laying hens,can partial alleviate the negative influences by lower nutrient levels in diet,and the purpose of saving feed resources was achieved.