A significant effect of neuropeptide Y was found on eggshell strength (p＜0.05) in female birds, and a significant effect of prolactin and dopamine D2 receptor gene was found on the body weight at 50 day in male birds (p＜0.05).

INTRODUCTIONSilky fowl (Gallus gallus var. domesticus) is so named in English because of its silky plumage. Silky fowl are distinct from other chicken breeds with their silky plumage; purple-colored skin; bluish meat; purple-to dark bluecolored wattles, beaks, and combs; green earlobes; a slightly upward pointing fifth hind toe; and beards and feathering on the feet. The average weight is 1.2 kg, which is slightly smaller than the other chickens, and the meat is firm and lean. Production efficiency is extremely low as only 50 to 200 laying eggs per year are produced. The meat and eggs are traded at high prices as a raw material in Chinese herbal medicine and as a health food good for nourishment tonics.In addition, Silky fowl have been kept as pets due to their unusual appearance.Internal hyperpigmentation has been observed in various organs of Silky fowl: perimysium of the muscle, the surface of bones, trachea, mesentery, digestive canals, ovary, and testis. Such visceral pigmentation is extremely rare in higher vertebrates (Muroya et al. 2000). Nozaki and Makita (1998) ABSTRACTThis study investigated the mechanism of melanin pigmentation in muscle and internal organs of adult Silky fowl and Rhode Island Red × White Plymouth Rock F1 broiler chickens, and the expression of three genes related to melanin pigment synthesis was examined. RT-PCR of tyrosinase (TYR) and two enzymes called tyrosinase-related proteins, dihydroxy indolcarboxylic acid oxidase (tyrosinase related protein 1; TYRP1) and DOPAchrome tautomerase (tyrosinase related protein 2; TYRP2) was performed for colon, cerebrum, middle kidney, heart, and shallow pectoral muscle tissues. Silky fowl expresses TYR, TYRP1, and TYRP2 in most organs, which suggests that melanin pigment was synthesized in most organs in Silky fowl.TYR was expressed in the cerebrum and heart even in the broilers without deposition of melanin pigment. TYRP1 and TYRP2were also expressed in some organs in broilers. Therefore, these genes may play a role other than melanin pigment synthesis in chickens.

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