Fifteen Years of Selection for Viability in White Leghorns

THE existence of genetic differences in resistance to specific diseases of chickens has been reported by many investigators. Likewise, selective breeding for general viability has been practiced with a fair degree of success by several workers. The pertinent information concerning work in these fields has been reviewed by Hutt (1949) and Jull (1952) and will not be covered thoroughly in this report. Briefly, however, diseases for which genetic resistance has been reported include avian diphtheria (Frateur, 1924), pullorum (Roberts and Card, 1926Roberts and Card, 1935; DeVolt et al., 1941), fowl typhoid (Lambert and Knox, 1928Lambert and Knox, 1932 a, 1932 b), leucosis (Asmundson and Biely, 1932; Gildow et al., 1940; Hutt et al., 1941; Jeffery et al., 1942; Taylor et al., 1943; Waters, 1945; Hutt and Cole, 1947, 1948; and others), “blue comb” disease (Cole, 1950) and a respiratory disease tentatively diagnosed as atypical infectious coryza (Lerner et al., 1950). Reduced mortality during the …