Production performance and intestinal tissue morphology difference of broiler breeders after leaving the cage in welfare breeding mode

【Objective】To investigate the effects of different breeding densities and activity space on production performance and intestinal tissue morphology of broiler breeders after leaving the cage for scientific and effective scheme of rational cull of broiler breeders.【Method】L-line hens of broiler breeders for culling aged 60 weeks with similar laying rate and body weight were selected. Then the floor rearing grouptreatmentⅠ, treatment Ⅱ and treatment Ⅲ and the cage rearing group(treatment Ⅳ) were set up, with 45 L-line hens in each treatment and 3 replicates per treatment.Culled broiler breeders in treatment I, treatment II and treatment Ⅲ were raised in pasture in floor breeding houses with space of 3.750, 1.875 and 1.875 hen/m² respectively. The method applied in treatment Ⅲ was welfare breeding with perches and sand bath. After 10 weeks of feeding, the amount of exercise, production and intestinal performance of the culled broiler breeders in each treatment were measured and analyzed to screen the breeding density and activity space suitable for the culled broiler breeders.【Result】The number of exercise steps of culled broiler breeders in each treatment in floor rearing group was significantly higher than that in cage rearing group(P<0.05, the same below), but the number in treatments Ⅱ, Ⅲ and Ⅰ significantly decreased in sequence. The laying rate, daily egg production and death rate of culled broiler breeders in cage rearing group were significantly higher than that in each treatment in floor rearing group, while the daily feed intake and feed to egg ratio were the opposite. The laying rate, daily feed intake and daily egg production of culled broiler breeders aged 70 weeks in treatment Ⅲ were significantly higher than that in treatment Ⅰ, but the daily feed intake was significantly lower than that in treatment Ⅱ. The eggshell strength and yolk weight of culled broiler breeders in cage rearing group were significantly lower than that in each treatment in floor rearing group, and the eggshell strength of culled broiler breeders in treatment Ⅰ was significantly lower than that in treatment Ⅲ. Compared with the cage rearing group, the villus height of duodenum, jejunum and ileum of culled broiler breeders aged 70 weeks in each treatment in floor rearing group significantly increased, while the crypt depth decreased. The villus height of duodenum, jejunum and ileum of culled broiler breeders aged 70 weeks in treatment Ⅲ were significantly higher than those in treatment Ⅰ, but lower than those in treatment Ⅱ, while the crypt depth was the opposite.【Conclusion】The production performance and intestinal tissue morphology significantly reduce after culled broiler breeders leave the cage. However, partial production performance, eggshell strength and intestinal function can be effectively improved by adding perches and sand bath to form a three-dimensional movement platform for floor rearing in the broiler breeder house with a feeding density of 1.875 hen/m². This method is suitable for reference and application in the process of broiler breeders culling.