| The problem of heat stress caused by the global temperature rise and the conversion of the breeding mode to intensification is an important factor restricting the economic benefits of the laying chicken breeding industry.The heat stress caused by the high temperature environment made the laying rate,feed intake,egg weight and feed egg ratio of laying hens seriously decreased,and the death washing rate and egg breakage rate increased significantly.It is of great significance to study the stress response characteristics of layer tissue system under high temperature environment and to explore the natural plant extract for improving the production of layer under hot environment,improving the product quality and reducing the mortality rate.This experiment in the laboratory on the basis of previous studies to explore the high temperature environment for laying hens laying rate,follicle development,reproductive hormone level and its receptor expression,rate of cell apoptosis in ovarian and antioxidant enzyme activity,etc,and the influence of curcumin is added in the normal temperature and high temperature environment for laying hens laying rate and the influence law of follicular development,provide theory support for the use of curcumin.Experiment 1: Effects of different doses of curcumin on egg yield and follicular development of laying hens at room temperatureA total of 144 Roman powder shell laying chickens aged 27 weeks,with similar body weight,health and similar production performance were selected and randomly divided into 4 groups.0 mg/kg,50 mg/kg,150 mg/kg and 250 mg/kg curcumin were added respectively.There were 6 replicates in each group and 6 chickens in each replicate.During the trial period,the illumination was 16 h/d,the intensity was10-15 lux,the pre-trial period was 2 weeks(27-28w),and the trial period was 9 weeks(29-37W).During the pre-trial period,various environmental indicators were adjusted to meet the requirements of the test.Test results:At room temperature,curcumin can improve the egg production rate,reduce the feed egg ratio and increase the egg weight of laying hens,and also reduce the breakage rate and death churn rate to a certain extent.Among them,curcumin has the largest increase range and the best effect when the added amount is 150mg/kg.In terms of reproductive hormones and receptors,curcumin treatment group significantly increased the serum and ovarian tissue FSH,LH,E2,P4 levels(P<0.05)and increase the relative expression level of corresponding hormone receptor in ovarian tissue(P<0.05).Comprehensive analysis showed that curcumin at 150mg/kg had the best effect.In terms of ovarian cell apoptosis,curcumin can reduce the apoptosis of functional cells in ovarian tissue of laying hens,among which the apoptosis rate is the lowest when the amount of curcumin is 150mg/kg.In terms of antioxidant enzyme activity,curcumin can significantly improve the activity of g SH-PX,SOD,CAT,TAOC and other antioxidant enzymes(P<0.05),reducing the concentration of LIPID peroxidation product MDA(P<0.05),When the curcumin content was 150mg/kg,the antioxidant enzyme activity of laying hens was the highest.To sum up,at room temperature,curcumin can improve the egg production rate and promote follicle development of layer hens at room temperature,and the best effect is achieved when the added amount of curcumin is 150mg/kg.Experiment 2: The influence of high temperature environment on laying rate and follicular development of laying hensSeventy-two Roman powder shell laying hens with similar weight,health and production performance were randomly divided into two groups,with 6 replicates in each group and 6 replicates in each group.The temperature in the high temperature group was maintained at 34±2 ° C,while that in the normal temperature group was maintained at 25±2 ° C.The humidity in each group was maintained at 65-80%.The trial period is 2 weeks(27-28W)and the trial period is 9 weeks(29-37W).The test results show that::In the continuous high temperature environment,the egg yield,feed intake,average egg weight,etc.of the layer chickens in the high temperature group were significantly reduced(P<0.05),the damage rate increased significantly(P<0.05),indicating that the high temperature environment significantly affected the performance of laying rate,egg breakage rate,feed intake and average egg weight of laying hens.In terms of follicular development,the number of follicles at all levels of laying hens in the high temperature group decreased significantly(P<0.05),indicating that high temperature directly affects follicular development;In terms of the expression levels of reproductive hormones and their corresponding receptors,compared with the normal temperature group,the serum and ovarian reproductive hormones FSH,LH,E2 and P4 of laying hens in the high temperature group were significantly decreased(P<0.05),the relative expressions of FSHR,LHR,ER and PR in ovarian tissue were significantly decreased,indicating that the high-temperature environment significantly affected the serum and ovarian reproductive hormone levels of laying hens as well as the relative expressions of their corresponding receptors in the ovarian tissue of laying hens.In terms of cell apoptosis in ovarian tissue,the apoptosis rate of laying hens in the high temperature group was significantly lower than that in the normal temperature group(P<0.05),indicating that the high temperature environment can induce the apoptosis of granulosa cells and membrane cells in ovarian tissue of laying hens.In terms of antioxidant enzymes,the activities of antioxidant enzymes such as GSH-PX,CAT,SOD and T-AOC in layer hens in the high temperature group were significantly decreased,and the concentration of lipid peroxide MDA was significantly increased,indicating that the high temperature environment would reduce the antioxidant capacity of layer hens’ serum and ovarian tissues.To sum up,under high temperature environment,high temperature environment will reduce the laying rate of laying hens,promote the apoptosis of granulosa cells and membrane cells in ovarian tissues,reduce the level of reproductive hormones in serum and ovarian tissues of laying hens and the relative expression of their corresponding receptors in ovarian tissues,inhibit the development of follicles,and at the same time,reduce the antioxidant capacity of laying hens.Experiment 3: Effects of different doses of curcumin on egg production rate and follicular development of laying hens under high temperature environmentA total of 144 Layers with Roman powder shell at 27 weeks of age,similar weight,health and similar production performance were randomly divided into 4groups,and 0 mg/kg,50 mg/kg,150 mg/kg and 250 mg/kg curcumin were added respectively.There were 6 replicates in each group and 6 chickens in each repeat.The temperature was maintained at 34±2℃ in the continuous high temperature group and25±2℃ in the normal temperature group.The pre-test period is 2 weeks(27-28W)and the trial period is 9 weeks(29-37W).The pre-test period adjusts various environmental indicators to meet the requirements of the test.The test results show that:In terms of production performance,compared with the high-temperature control group,curcumin can improve the egg production rate of laying hens under continuous high temperature environment,among which the egg production rate increases the most when the added amount of curcumin is 250mg/kg(P<0.05);In terms of reproductive hormones,curcumin can increase the serum levels of FSH,LH,E2 and P4 in laying hens and ovarian tissues under high temperature environment,and increase the relative expression levels of FSHR,LHR,ER and PR m RNA in ovarian tissues.Comprehensive analysis shows that the best effect is achieved when the added amount of curcumin is 250mg/kg.In terms of antioxidant capacity,curcumin can increase the antioxidant enzyme activities of serum and ovary tissues of laying hens,such as GSHPX,SOD,CAT and T-AOC,among which the antioxidant enzyme activities of laying hens are the highest when the added amount of curcumin is 150mg/kg and 250mg/kg.In summary,curcumin can improve the egg production rate and promote the follicle development of laying hens under high temperature environment.When the added amount of curcumin is 250mg/kg,it has the best effect on the egg production rate and follicle development of laying hens,which is still significantly different from the normal temperature control group,indicating that curcumin has not recovered to the normal temperature level after being added. |
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