対馬地鶏卵肉兼用鶏における卵の特徴.

The Tsushima-jidori are a native breed of chickens in Tsushima City, Nagasaki Prefecture, and have long been kept as egg-laying hens in garden poultry farms. In order to improve the egg-laying ability of Tsushimajidori, they were crossed with red eggshell laying hens, which have higher egg-laying ability, and the egg-laying characteristics of the crossed hens were investigated. The crossbred chickens were found to have higher egg - laying ability than the Tsushima-jidori, a more elongated egg shape compared to the red eggshell laying hens, and an eggshell color of pink to almost reddish-brown. The general egg composition showed inherited characteristics of both Tsushima-jidori and red eggshell hens. The large yolk ratio is a characteristic of Tsushimajidori hens, and hens resulting from crossbreeding with Tsushima-jidori hens inherited the same characteristics. Further, eggshell thickness and strength, and Haugh unit were improved by crossbreeding with red eggshell hens. These results suggest that crossbred Tsushima-jidori hens can inherit characteristics of the original Tsushimajidori hens while exhibiting high egg-laying ability and producing distinctive eggs. [ABSTRACT FROM AUTHOR]