Effects Of Coated Trace Elements On Performance And Intestinal Function Of Laying Hens

The purpose of this paper was to study the effects of coated trace elements on the production performance and intestinal function of laying hens,and to provide theoretical support for the application of coated trace elements in the later stage of laying.This paper was divided into two experiments: the release efficiency of coated trace elements and the effects of coated trace elements on laying hens on production performance and intestinal function.Test 1 Study on release efficiency of coated trace elementsCoated trace elements were dissolved in sodium chloride hydrochloric acid buffer solution with p H of 3.0,4.0 and 6.0.Refer to the operation process of the second method（slurry method）of 0931 dissolution and release determination method in part IV of 2020 edition to determine the in vitro dissolution efficiency,and the dissolution time was 1h.Secondly,a total of 72 white feather broilers at 42 d with similar healthy weight were randomly divided into two treatments,with six repetitions in each treatment and six chickens in each repetition.Remove the trace elements in the test premix and add 450 mg/kg coated trace elements on this basis.Treatments 1and 2 were fed with coated trace elements for 1h and 2h,respectively.The pre experiment period was seven days and the formal experiment is one day.At the end of the experiment,the serum and small intestine were collected,and the trace elements in the dissolution solution were determined by atomic absorption spectrophotometer to calculate the release efficiency of trace elements.The test results are as follows:（1）Verify that the coated trace elements could be sustained-release in different p H simulation solutions.（2）It was verified that the coated trace elements could be sustained-release in the duodenum,jejunum and ileum of broilers.Test 2 Effects of coated trace elements on performance and intestinal function of laying hensTest take 2 × 3 experimental design: 1620 65 week old Hy-line laying hens with similar healthy weight were randomly divided into six treatments,with six repetitions in each treatment and 45 chickens in each repetition.The trace elements in the test premix are eliminated.On this basis,inorganic trace elements of 300,450 and 600mg/kg were added in ITE 300,450 and 600 groups respectively,and coated slow-release composite trace elements of 300,450 and 600 mg/kg are added in CTE300,CTE 450 and CTE 600 groups respectively.The test period was 70 days.On the day of the end of the test,eggs,serum,tibia,muscle,feces and intestine were collected.The test results were as follows:The coating treatment group significantly improved the eggshell strength and eggshell thickness of laying hens（P < 0.05）.With the increase of concentration gradient,the average egg weight,eggshell strength and eggshell thickness increased significantly（P < 0.05）,the feed egg ratio decreased significantly（P < 0.05）,and reached the optimal state in CTE450 group.（2）The coated group significantly increased the contents of serum T-SOD and GSH-PX and decreased the content of MDA（P < 0.05）.With the increase of concentration gradient,the contents of serum T-SOD and GSH-PX increased significantly（P < 0.05）,and the content of MDA decreased significantly（P < 0.05）.（3）The coated group significantly increased the contents of Mn in serum,Cu,Fe and Zn in bone,Zn in muscle,Cu,Zn and Mn in egg yolk（P < 0.05）.With the increase of concentration gradient,the contents of Cu,Fe,Zn and Mn in serum,muscle and egg yolk increased significantly（P < 0.05）.（4）The coated group significantly increased V/C and decreased recess depth（P < 0.05）.With the increase of concentration gradient,the depth of recess decreased significantly（P <0.05）and the ratio of velvet to concealment increased significantly（P < 0.05）.（5）The coated group significantly increased the m RNA and protein expression of DMT1,Zn T-1 and FPN1 in duodenum（P < 0.05）.With the increase of concentration gradient,the m RNA and protein expressions of DMT1,Zn T-1 and FPN1 in duodenum increased significantly（P < 0.05）.The above results show that coated trace elements could be dissolved and released in poultry.Adding coated trace elements to the diet could significantly improve the quality of eggs,improve the antioxidant capacity of the body and the storage of trace elements in blood and tissues,significantly reduce the emission of trace elements in feces,improve the intestinal environment and increase the absorption and utilization of trace elements.CTE450 group was the most suitable for production benefit without affecting production performance.