Effects Of Rare Earth Additives On Performance,Serum Biochemical Indexes,Antioxidant Capacity And Intestinal Health Of Laying Hens

This experiment was conducted to study the effects of rare earth additives on the performance,serum biochemical indicators,antioxidant capacity and intestinal health of380 day old Roman powder laying hens in the late laying stage.In this experiment,960 Roman powder laying hens of 380 days old with balanced production performance were randomly divided into five treatment groups,with 6replicates in each group and 32 chickens in each replicate.The control group was fed with basic diet,and the experimental group was fed with experimental diets supplemented with150 g / t,300 g / t,450 g / t and 600 g / t rare earth additives respectively.The experimental period was 21 days.Experiment 1: Accurately record the total number of eggs laid,the total weight of eggs and the number of dead eggs for each repetition every day.The total feed intake shall be settled every week,and the average daily feed intake shall be calculated every week.At the end of the third week of the experiment,four eggs with similar color and uniform size were selected from each repetition,weighed by electronic balance,measured by vernier caliper the length and short diameter of the eggs,measured the strength and height of the eggshell,scored the color of the yolk,measured the thickness of the eggshell and calculated the Huff unit.The results showed that: 1)compared with the control group,each experimental group had no significant effect on the laying rate,average daily feed intake and feed egg ratio of laying hens treated for 21 days in the later stage of laying(P > 0.05).However,with the passage of time(1-3 weeks),the average egg weight of 150 g / t and300 g / t groups increased.2)Compared with the control group,the egg shell thickness of150 g / t,300 g / t,450 g / t and 600 g / t groups was significantly thinner on day 21(P <0.05).It can be seen that adding 150 g / t and 300 g / t rare earth additives to the diet can improve the average egg weight of laying hens in the later stage of laying,but reduce the eggshell thickness in egg quality.Experiment 2: Determine the content of total protein TP,calcium Ca,high-density lipoprotein HDL-C,low-density lipoprotein LDL-C,total cholesterol T-CHO,triglyceride TG,urea nitrogen BUN,glucose GLU and phosphorus P in serum with microplate reader.The total protein of egg yolk and liver was determined by colorimetry,and then the antioxidant indexes of serum,egg yolk and liver tissue homogenate were determined.The contents of MDA,T-AOC,GSH-PX,SOD and GSH were measured by microplate reader.The results showed that: 1)compared with the control group,adding 300 and 450 g /t rare earth additives to the diet significantly increased the content of serum HDL in laying hens(P < 0.05).2)Compared with the control group,the addition of rare earth minerals in the diet had no significant effect on the contents of T-AOC,MDA and GSH in egg yolk(P > 0.05).3)Compared with the control group,the addition of 600 g / t rare earth mineral in the diet significantly increased the GSH PX activity in serum and liver of laying hens,and the addition of 450 g / t rare earth mineral significantly increased the GSH PX activity in liver(P < 0.05).In conclusion,rare earth additives can increase the concentration of serum high density lipoprotein,improve the antioxidant capacity in vivo and reduce the oxidative stress in laying hens.Experiment 3: Observe the intestinal morphology and structure by making intestinal tissue sections,and analyze the composition of intestinal flora by sequencing.The results showed that: 1)compared with the control group,adding 600 g / t rare earth additive to the diet significantly increased the depth of ileal recess(P < 0.05).2)The dominant species of cecal contents in each group at the phylum level are Bacteroidetes and Firmicutes,but the richness of all phyla is different.At the cecal microbiota level,adding a certain dose of rare earth additives to the diet could promote the decrease of Clostridium abundance(P < 0.05),At the genus level,adding a certain dose of rare earth additives to the diet could reduce the abundance of Clostridium and increase the microbial abundance of rumen cocci and dysosmobacter welbionis(P < 0.05)α Diversity had little effect(P < 0.05)β Diversity analysis showed that adding 600 g / t rare earth additive in diet was significantly different from other groups.In conclusion,the addition of high dose of rare earth additives in the diet will damage the morphology of the intestine.An appropriate amount of rare earth additives can improve the intestinal microorganisms of laying hens in the later stage of laying,and the addition of rare earth additives in the diet can improve the intestinal microbial function of laying hens in the later stage of laying.