A Comparative Study On The Production Performance,Immune Level And Intestinal Microflora Of Laying Hens Between Two Stacked Cages

With the acceleration of the transformation and upgrading of laying industry in China,the proportion of standardized and large-scale poultry house is gradually increasing,and the scale of laying hens is increased,so the health of laying hens is becoming more and more important to ensure the performance of laying hens.However,this kind of high stocking density mode are due to differences in breed,biosafety,immunization procedures and environmental controls,which will affect the health status and immune level of the birds in the production system.Therefore,the study was conducted to investigate the air environment quality in the two large scale hens houses（50,000 hens in single house and 100,000 hens in single house）,and the differences of the production performance,immunity level and gut microbes were explored in the 39-48-week-old Romanpink-shell commercial laying hens in the houses.This study could provide a reference for optimizing the large-scale laying hen production system,promoting the health and improve production performanceof laying hens.1.Air environmental quality in different scale laying hen houses:There were no significant differences on temperature,relative humidity,air velocity,concentrations of NH3and CO₂ between the two scale layers houses（P>0.05）.The light intensity in the house with50,000 laying hens was significantly higher than that of the house with 100,000 laying hens（P<0.05）.2.Production performance and specific antibody level of layers in different scale laying hens houses:There was no significant differences on laying rate of hens in the two scale hens houses（P>0.05）.The average egg weight of birds in the single house with 100,000laying hens was 2.54%higher than that of birds in the single house with 50,000 laying hens（P<0.05）,and the yolk color was 5.77%lower than that of birds in the single house with50,000 laying hens（P<0.05）.The differences were found in antibody levels of avian influenza H5 strain of laying hens in different scale hens houses（P<0.05）.The antibody titer of avian influenza H5 of birds in the single house with 100,000 laying hens was 3.30%higher than that of birds in the single house with 50,000 laying hens（P<0.05）.3.Indexes of serum antioxidant and immune factors of layers in different scale laying hens houses:the contents of antioxidant indexes GSH-Px,T-AOC and SOD in laying hens were significantly different（P<0.05）in different scale houses,and the difference value reached the maximum at the back end,back end and front end of the two chicken houses（P<0.05）.There were no significant differences in serum CORT and MDA（P>0.05）.There were significant differences in immune levels of IL-1β,IL-2,IL-6 and TNF-αcontents of laying hens in different scale houses（P<0.05）.4.Intestinal mucosal morphology and bacterial colony structure of layers in different scale laying hens houses:The duodenal crypt depth of laying hens in the single house with50,000 layers was 9.09%smaller than that of laying hens in the single house with 100,000layers（P<0.05）.Relative expression abundance of Bacteroidetes in the duodenum of laying hens in the single house with 50,000 layers was 47.6%lower than that of laying hens in the single house with 100,000 layers（P<0.05）.Relative expression abundance of Koelobacter in the cecum of laying hens in the single house with 50,000 layers was 15.0%higher（P<0.05）than that of laying hens in a single house with 100,000 layers,and relative expression abundance of Bacteroidetes in duodenum in the single house with 50,000 layers was 51.7%lower（P<0.05）than that of laying hens in the single house with 100,000 layers.In conclusion,there was no significant difference in the main environmental parameters and production indexes such as temperature,relative humidity,NH₃ concentration and egg production rate of layers in the two scale houses except light intensity,egg weight and yolk color（P>0.05）.the overall antioxidant capacity and immune level in the single house of50,000 layers were better,and the relative expression abundance of Bacteroidetes duodenum and Koelobacter cecum was higher.