Journal Article
Genetic improvement by selection for decrease of the meat spots in Nagoya breed [2007]
Noda, K.(Aichi-ken. Agricultural Research Center, Nagakute (Japan)); Nakamura, A.; Kino, K.; Katoh, Y.;
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The purpose of the present study was to look for a way to decrease the meat spots in brownish eggshell colored chickens. Nagoya breed laying pink shell-colored eggs was used in this study, all eggs laid by each individual bird for three consecutive days (270 days of age) were broken out and then internal meat spots were measured for the size of area. Selection was applied to use the independent culling level method setting a certain level for area of the meat spots. The following conclusions were obtained ; After four generations of selection, heritability estimates for area of the meat spots were low, ranging from 0.00 to 0.13. Although area of the meat spots tended to be small, the realized genetic gain per generation for area of the meat spots was apparently negative (-0.25 square mm ; P0.05). Birds with area of meat spots over 3 square mm showed highly significant decreases with the passage of generations (10% in a base generation and 2% in generation 4 ; P0.01). Furthermore, birds with absence of the meat spots were increased significantly (30% in a base generation and 37% in generation 4 ; P0.05). The phenotypic correlation between the area of the meat spots and the economic traits, egg shell color (L value), was low. However the effect of decrease of the meat spots on some economic traits was not clear. The results of this experiment results suggest that this method of selection for smaller areas of the meat spots is an efficient way of decreasing i
ncidence of the meat spots.
