Effects of Caponization on Growth Performance and Carcass Traits in Hinai-jidori Chicken

Hinai-jidori is a popular brand chicken in Japan. Most Hinai-jidori chickens commercially available are females; in contrast, male chicks have been unused. To make unused male Hinai-jidori chicks more usable, an experiment was conducted to examine whether caponization influences growth performance and carcass traits in Hinai-jidori chicken. Hinai-jidori chicks were divided into female, capon, and male groups of 15 birds at 4 weeks of age. Male chicks in the capon group were caponized at 8 weeks of age. Five birds from each of the three groups were slaughtered at 22, 26 and 30 weeks of age, respectively. In the live body weight and daily weight gain, there was no significant difference between the capon and male groups from 18 to 26 weeks of age, while the female group showed the least live body weight and daily weight gain among the three groups throughout the experimental period. In the carcass traits, the capon group showed higher proportion of whole leg and total meat than the female group at 26 and 30 week of age. The capon group had heavier abdominal fat weight than the male group at 26 weeks of age. There was no significant difference in the proportion of abdominal fat between the two groups at all weeks of age. Since capons gain body weight equivalent to males until 26 weeks of age and gain abdominal fat comparable to females, caponization is useful to apply Hinai-jidori males to commercial use.