A Comparison of the Mortality of Single Comb White Leghorn Growing Pullets and Laying Hens

DURING recent years considerable attention has been given to the problem of increasing the viability of the domestic fowl. Marble (1939) and Sturkie (1943) have shown that the viability of the hen can be influenced by careful selective breeding. Taylor and Lerner (1938), Bearse et al. (1939), Hutt et al. (1941), and Bryant and Johnson (1944) have reported the development of resistant and susceptible or low- and high-mortality strains. In breeding for viability it would seem desirable, if possible, to eliminate the families with a high incidence of mortality, before the pullets reach the laying quarters. The study reported in this paper was made to determine whether there is any relationship between the losses from death during the growing period and the first laying year. PROCEDURE The birds used in this experiment were Single Comb White Leghorns: The study extended from the spring of 1938 to the fall of 1943. . . .