Research Abstract |
Quantitative trait locus (QTL) analyses were performed to map QTLs controlling growth-related traits (e.g., body weight, shank length), egg-related traits (e.g., egg weight, egg production rate), and meat-related traits (e.g., pH value, meat color) in an F2 resource family developed from a cross of the large-sized, native Japanese cockfighting breed, Oh-Shamo (Japanese Large Game) and the White Leghorn breed of chickens. All in all, 37, 33, and 29 traits were analysed in growth-, egg-, and meat-related traits, respectively. Interval mapping revealed many significant QTLs for many traits as shown below. (1) Growth-related traits: A QTL for shank length at 14 and 16 weeks of age was found on chromosome 4. Three QTLs for shank length at 20 weeks of age were detected on chromosomes 1, 4, and 24. In addition, a QTL controlling 20-week body weight and carcass weight was found on chromosome 4. (2) Egg-related traits: A QTL for egg weight at 300 days of age was detected on chromosome 4. Two QTLs for egg production rate at 400 days of age were identified on chromosomes 3 and 4. A QTL for L^* value of eggshell color was discovered on chromosome 3. Furthermore, two QTLs were found on chromosomes 4 and 11 for egg yolk weight at both 300 and 400 days of age. (3) Meat-related traits: A QTL was identified on chromosomes 4, 13, 3, and 1, respectively, for the pH value of the leg muscle, b^* value of the leg muscle color, b^* value of the deep breast muscle color, and the myoglobin contens in the deep breast muscle. It seems that the discovery of the QTLs for these meat-related traits and the shank length trait mentioned above is the first discovery in the world.
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