Effects Of Cages With Different Sizes On The Production Performance, Serum Biochemical Index And Intestinal Health Of Laying Hens

This study takes Roman pink shell commercial laying hens as experimental subjects and we carry out the study under the density of 540cm2 per cage layers in an eight story chicken house to research the effects of different size cages(extra-large cages,large cages,medium cages and small cages)on production performance,serum biochemical indices and intestinal health of layers in the middle and late laying period.The results provide the basis for optimizing the breeding technology,promoting the production performance and body health of stack-up laying hens in cage.The results are shown as follows:1.Production Performance: Under the condition of constant rearing density,the performance of layers could be improved by increasing cage size appropriately.By comparing with the small cage group,laying rate of middle cage group is increased by 3.19%and its feed to egg ratio is decreased by 4.70%;the body weight gaining of small cage group is significantly higher than that of other groups,accounting 124.98%,99.79% and 59.33%higher than that of medium cage,large cage and extra-large cage groups,respectively(P <0.05).There is no significant difference in average egg weight among all groups(P > 0.05).2.Immunity level: The antibody titers of layers raised in different kinds cages are significantly different at 54 and 57 weeks of age.At age of 54 weeks,the antibody titers of large cage and medium cage groups are significantly higher than those of extra-large cage and small cage groups(P < 0.05);at age of 57 weeks,the antibody titers of H9N2 in large cage and medium cage groups are significantly higher than that in extra-large cage and small cage groups(P < 0.05).3.Serum biochemistry: The contents of triglyceride(TG)and total cholesterol(T-CH)in extra-large cage group are significantly lower than those of other groups(P < 0.05);the contents of TG and T-CH in large cage and medium cage groups were significantly lower than those of small cage group(P < 0.05);the activity of glutathione peroxidase(GSH-Px)in extra-large cage and large cage groups is significantly higher than that in medium cage and small cage groups(P < 0.05);there is no significant difference in other serum biochemical indexes among all groups(P > 0.05).4.Intestinal morphology: Villus heights of duodenum in middle cage group are significantly higher than that of extra-large cage and large cage groups(P < 0.05);crypt depths of duodenum in small cage group are significantly higher than that of extra-large cage(P < 0.05);and villus height-crypt depth ratio of duodenum in extra-large cage and middle cage groups is significantly higher than that in large cage and small cage groups(P< 0.05).5.Intestinal bacterial colony structure: Duodenal microbial richness and cecum microbial diversity in large cage group are higher than those in other groups;the relative abundance of beneficial bacteria(Faecalibacterium)in cecum of middle cage group is significantly higher than that of other groups.In conclusion,middle cage rearing is more beneficial to improve laying rate,feed conversion rate,lipid metabolism level,duodenal morphology and intestinal microbe distribution of layers in middle to late laying period.The effects of different cage sizes on other layers in different growth stages need to be further studied.