An efficient method of early caponization in slow-growing meat-type chickens.

We developed a new tool for testectomy and investigated the efficiency with regard to caponizing time and growth performance in Hinai-jidori chickens, a popular breed of chicken in Japan. Hinai-jidori chicks were divided into 2-, 4-, and 8-wk caponized groups and an intact male group (20 birds/group) at 2 wk of age and were raised until 26 wk of age. The testes of the male chicks caponized at 8 wk of age were surgically removed from both sides using a Japanese traditional tool, whereas those of male chicks caponized at 2 and 4 wk of age were surgically removed from only one side using the new tool. Using the traditional method, caponization of an 8-wk-old chick was achieved in 324.6 s (5 min 24 s), whereas using the new method, caponization of 2- and 4-wk-old chicks was achieved in only 35.9 and 28.4 s, respectively. Moreover, at 10 and 18 wk of age, the chicks caponized at 4 wk of age were significantly heavier than the chicks caponized at 8 wk of age. The data suggest that the decrease in the daily weight gain caused by caponization at a younger age was less than that at an older age. We concluded that early caponization shortens the caponizing time significantly and improves the decrease in the daily weight gain after caponization, thereby enabling efficient capon production from slow-growing meat-type chickens at early stages of development.