Embryonic and Chick Mortality of Four Native Japanese Chicken Breeds

The objective of the present study was to survey embryonic and chick mortality in native Japanese chicken breeds (Onaga-dori; ONA, Tosa-jidori; TJI, Ukokkei; UKO and Hinai-dori; HNI). The embryonic mortality for each breed was 45.7 (ONA), 51.7 (TJI), 42.9 ( UKO) and 26.7% (HNI), throughout the incubation period. The ONA and TJI were found to show high mortality at the early embryonic stage (1-7 days) and it accounted for approximately 70% of total embryonic mortality. In the UKO, high mortality was detected at both the early and late (15-21 days) stages of incubation. Total chick mortalities up to 10 weeks of age were 68.0 (ONA), 62.8 (TJI), 26.4 (UKO) and 6.0% (HNI). In the ONA and TJI, higher mortalities were observed during the 2nd and 3rd week periods of life and reached more than half of their mortalities. The UKO was found to show the highest mortality during the 1st week of life. The HNI exhibited no specific mortality trends throughout the experiment period. These results suggest that embryonic and chick mortalities in Japanese chicken breeds are controlled by genetic factors. Changes in the management routines for each breed might reduce embryonic and chick mortalities and lead to the conservation of these rare Japanese chicken breeds.