ABSTRACT
Objective To analyze the changes and gender differences of organ coefficients, intestinal length and body size of SJ5-SPF chickens at different weeks of age,and to provide experimental data for the sex selection of laboratory chickens. Methods The body weight,the weight of 15 main organs,and length of 5 main segments of intestine and the 6 main parameters of body size of SJ5-SPF chickens at the age of 4,20,25 and 40 weeks were measured,respectively,and the organ coefficients were calculated. In addition, the gender differences in body weights, organ coefficients, intestinal lengths and body sizes between the female and male SJ5-SPF chickens at the four different weeks of age were compared, respectively. Results There were significant differences in body weights between the male and female SJ5-SPF chickens at each of the four different weeks of age(P < 0.01). The organ coefficients varied between females and males to different extents at different weeks of age. As for the intestinal length,there were no significant differences in the length of jejunum and ileum as well as rectum between the male and female chickens, while the length of duodenum, left cecum and right cecum showed gender differences at some of the four different weeks of age. During the determination of body size, there were gender differences in body length,shank length,pelvic width,chest depth and chest width at two or three of the four different weeks of age. Conclusions The organ coefficients, intestinal length and body size of SJ5-SPF chickens are affected by both their age and gender.