The Death Rates of Three Standard Breeds of Fowl

Among the characteristics of breeds of domestic animals which may be of economic importance as well as of biological interest are their relative death rates. Earlier studies have dealt with the problem of the differentiation of birds which died at some time during their first laying years from those which survived throughout that period. In these papers it has been shown that in the White Leghorn * and in the White Wyandotte and Rhode Island Red breeds of fowl ** the means, standard deviations, and coefficients of variations of the monthly egg production of these two classes, those which survived and those which died, are significantly different in many months of the year. The results have been confirmed by the application of other biometric criteria. *** While these studies deal adequately with the problem of the differentiation with respect to egg production of birds which survive for various periods of time, they leave . . .