Abstract
Analyses were performed on the published data of four years' prefectual random sample tests held in Japan from 1962 to 1966 and also on the combined two years summary of the U.S. test for 1963-64 and 1964-65, to determine which of the traits had the greatest influence upon the income over feed and chick cost.
Seven traits were analysed in Japanese data and fifteen were in the U.S. data for linear correlation and regression, but only seven in the U.S. test, which had direct correspondence with the traits of Japanese test, were used for multiple regression analysis. Those were:
Japanese test U.S. test
X1=Growing viability X1=Growing mortality
X2=Laying viability X2=Laying mortality
X3=Age at 50% production X3=Age at 50% production
X4=Hen-day production X5=Hen-day production
X5=Feed conversion X6=Feed per pound of eggs
X6=Egg weight X7=Egg weight
X7=Body weight at end of test X9=Body weight at end of test
Y=Income over feed and chick cost Y=Income over feed and chick cost
It was found that regression on all seven traits removed 89.4% and 89.2% of the variation in income in Japanese and U.S. data respectively. Feed conversion was the most important trait in Japan, which removed 65.6% of the variation and adding the second importat trait, laying viability, removed 83.1%, and further addition of the third trait, hen-day production, accounted for 88.3% of the income variation. The order of remaining four traits was growing viability, age at 50% production, egg weight and body weight. The corresponding order in the U.S. data were egg production, feed per pound of eggs, egg weight, laying mortality, age at 50% production, growing mortality and body weight. The remarkable difference of importance in egg weight would be reflected by marketal situations between two countries.
The financial returns expected by accounting both direct and correlated responses were discussed.
