Effects Of Large-Scale Cascading Cages On The Serum Biochemical,Immune Levels And Intestinal Health Of Laying Hens

The present study was conducted in a layer house with eight-layer cascading cage.The standard cascading cage(small cage)and the modified large-scale cascading cages(huge cage,large cage and medium cage)were selected to raise Roman laying hens(32 to 39weeks of age)under the same rearing density(450 cm~2per bird).The effects of large-scale cages with different sizes on the laying performance,serum biochemistry,immunity and intestinal health of laying hens during peak laying period were investigated.The results are as follows:1.Laying performance:The average laying rate of medium cage group was the highest while the ratio of feed to egg was the lowest(P<0.05).The average laying rate of medium cage group was 3.19%,2.80%and 2.12%higher than the large cage,small cage and huge cage group,respectively.The average feed to egg ratio of the medium cage group was5.96%,4.65%and 5.53%lower than the huge cage,large cage and small cage group,respectively.The average body weight gain in the huge cage group was significantly higher than that in the other groups(P<0.05).The average egg weight of the medium cage group was significantly higher than that of the other groups(P<0.05).2.Egg quality trait:The albumen height of small cage group was significantly lower than medium cage group(P<0.05).The Haugh unit and eggshell color of large cage group and medium cage group were higher than those of small cage group(P<0.05).3.Immune level:The antibody titers of H5N1 and H9N2 in the huge,large and middle cage groups were higher than those in the small-cage group at 34,36 and 38 weeks of age,but the difference was not significant(P>0.05).The antibody titers of ND of laying hens in huge cage,large cage and medium cage groups were significantly higher than that in small cage group at 36 and 38 weeks of age(P<0.05).4.Serum biochemistry:Serum LDL,CORT,MDA concentration of laying hens in the medium and the small cage groups were significantly higher than those in the large and huge cage groups(P<0.05).Serum BUN,Ig G concentration of laying hens in the medium cage group were significantly higher than those in the other groups(P<0.05).Serum Ca and HDL concentration of laying hens in the huge cage group were significantly higher than those in the other groups(P<0.05).5.Intestinal morphology:Duodenal villus height of laying hens in the medium cage group was significantly higher than that in the other groups(P<0.05),while the villus height to crypt depth ratio of laying hens in the small cage group was significantly lower than that in the other groups(P<0.05).6.Cecal microbiota compositio:The abundance,homogeneity and species diversity of the huge cage group were higher than those of the other groups,but there was no significant difference among the groups.The relative expression of beneficial bacteria Phocaeicola and beneficial phylum Firmicutes in cecum of laying hens in huge cage group was higher than those in other groups.In conclusion,the medium cage was superior to other cages in improving egg production performance and lipid metabolism,An appropriate increase of the cascading cage size may conductive to enhance the the immune level and intestinal health performance of laying hens.