| In this experiment,Eucommia Ulmoides Oliver Extract(EUOE)was used as the research object to explore effect of adding EUOE in the diet on the alleviation of osteoporosis of cages layers in late laying period.Experiment 1: Effects of EUOE on production performance,egg quality and bone index of laying hens in late laying periodA total of 512 470-day-old Hy-Line brown laying hens in late laying period were randomly divided into 4 treatment groups,including control group and three EUOE supplement groups,with 8 replicates per group and 16 hens per replicate.Hens in control group were fed a basal diet,and those in experimental groups were fed the basal diet supplemented with 500 g/t,1000 g/t and 2000 g/t EUOE,respectively.The experiment lasted for 64 days.The results showed that: 1)Compared with the control group,there were no significant effects on the laying rate,average egg weight and feed to egg ratio of laying hens treated at 32 and 64 days(P>0.05).However,as time passed(1-9W),the laying rate of laying hens in the control group,500 g/t and 2000 g/t groups decreased by6.88%,4.03% and 4.53%,respectively,while the supplementation of 1000 g/t EUOE could maintain the laying rate at a certain level in late laying period.And the mortality rate of laying hens in 1000 g/t group was the lowest compared with the other groups.2)Compared with the control group,on the 32 days of the test,the Hastelloy unit and protein height of the eggs in the 1000 g/t group were significantly increased(P<0.05),and the eggs in the 2000 g/t group were abnormal(cracked,deformed,and soft).The rate of dirty eggs has a significant upward trend(P=0.08),and the dirty egg rate has a significant downward trend(P=0.082).On the 64 th day of the test,the abnormal egg rate of the layers in the 500 g/t group was significantly increased(P<0.05),and the thickness of the eggshell of the layers in the 2000 g/t group was significantly decreased(P<0.05).On the 32 nd and 64 th day of the experiment,the dirty egg rate of the 1000 g/t group and2000 g/t group of laying hens decreased significantly(P<0.05).3)Compared with the control group,liver index of laying hens in 2000 g/t group was significantly increased(P>0.05),the tibia length had a significant tendency to increase(P=0.062),but the tibia index(P=0.054)had a tendency to decrease.However,the spleen index,tibia weight and femur weight of laying hens in 1000 g/t group were significantly increased(P>0.05),but there were no significant changes in tibia index and femur index.Compared with the control group,the tibia length and femur length of laying hens in 500 g/t and 1000 g/t groups were significantly increased(P>0.05).In conclusion,the supplementation of1000 g/t EUOE in the diet can delay the decrease of laying rate at a certain level,improve the egg quality at 32 days,and increase the bone quality indexes such as the weight and length of tibia and femur.Experiment 2: Effect of EUOE on the changes of related regulatory factors of bone tissue metabolism and development of laying hens in late laying period384-day-old hens were set as 3 processing groups individually.There are 8replicates per group,16 plumes per repeat.The control group was fed basic diet,and the experimental group was fed 1000 g/t,2000g/t EUOE of experimental diet for 64 d,respectively.The results showed that: 1)Compared with the control group,the thickness of femoral cortical bone and cortical bone area of the layers of 1000 g/t group and 2000g/t group increased significantly(P<0.05),and the percentage of cortical bone area increased significantly in 2000 g/t group(P<0.05).About the femoral tissue structure of the experimental group,2000 g/t were better than that of the 1000 g/t group.2)Compared with the control group,the serum estradiol(E2)content in the 2000 g/t group was significantly decreased(P<0.05),but serum alkaline phosphatase(ALP)level was significantly increased(P<0.05).3)Compared with the control group,the relative expression of tibia sphingosine kinase 1(SPHK1)and ALP m RNA in the 1000 g/t group increased significantly(P<0.05),while that of sphingosine 1-phosphate receptor(S1PR)increased(P=0.072).When the add amount of EUOE was 2000 g/t,the m RNA expression of tibial SPHK1,S1 PR and osteoprotegerin(OPG)in laying hens increased significantly(P<0.05).Compared with the control group,both the relative expression of receptor activator of nuclear factor κ-B(RNAK)and receptor activator of nuclear factor-κB ligand(RANKL)m RNA were significantly down-regulated(P<0.05)in group1000 g/t and group 2000 g/t.In summary,EUOE has promoting effects on the bone morphology and structure of laying hens.At the same time,it increased the content of serum bone anabolism and reduced the content of serum bone resorption metabolism markers,and increased the relative expression of m RNA of regulatory factors that promote bone formation and inhibit bone resorption.The potential mechanism may involve OPG/RNAKL/RNAK and SHPK/S1 P signaling pathways.Experiment 3: Effects of EUOE on bone calcium-phosphorus metabolism and bone collagen metabolism of laying hens in late laying period384 Hy-line brown laying hens,aged 470 days,were randomly divided into 3groups with 8 replicates per group and 16 hens per replicate.The control group was fed with basal diet,while the experimental group was fed with basal diet supplemented with1000 g/t or 2000 g/t EUOE respectively.This experimental period was 64 days.The results showed that: 1)Compared with the control group,the density of tibia in 1000 g/t group and 2000 g/t group increased by 2.63% and 4.61%(P>0.05),respectively.However,the maximum deflection of tibia in 1000 g/t group was significantly increased(P<0.05).2)Compared with the control group,the serum parathyroid hormone(PTH)of laying hens in the 2000 g/t group showed a significant upward trend(P=0.077),and the serum procollagen Ⅰ c-terminal propeptide(PICP)content of laying hens in each experimental group was significantly increased(P<0.05).Compared with the control group,the serum calcitonin(CT)and PTH in the 1000 g/t group were significantly decreased(P<0.05).But,the serum Ca and Mg levels in 2000 g/t group were significantly increased(P<0.05).3)Compared with the control group,the addition of EUOE at 1000 g/t and 2000 g/t in the diet could significantly down-regulate the relative expression level of fibroblast growth factor receptor(FGFR)m RNA(P<0.05).The relative expression level of BMP2 m RNA significantly increased(P<0.05)in the tibia of laying hens of 1000 g/t group.When 2000 g/t EUOE was added to the diet,the relative expression level of matrix metalloproteinase 9(MMP9)m RNA in the tibia of laying hens showed a significant downward trend(P=0.063),while the relative expression levels of Type Ⅰ Collagen α 1(COL1A1)and Type Ⅰ Collagen α 2(COL1A2)m RNA were significantly increased(P<0.05).It can be concluded that EUOE could significantly regulated the changes of related regulatory factors of calcium-phosphorus and collagen metabolism,and EUOE was helpful to promote the increase of bone elasticity and bone collagen formation of laying hens. |
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