Selection for Egg Production in the Domestic Fowl Under Normal and “Short Day” Environments

DRYDEN (1921), Hall (1938), Hays and Sanborn (1934), and Lerner (1950), all demonstrated that artificial selection when practiced over many generations, resulted in a marked increase in egg production. Although substantial gains were noted, it is obvious that the environment improved during these long periods and, therefore, the total gain in egg production may not have been the result of genetic improvement alone. There is substantial evidence indicating that while considerable progress can be obtained during the early generations of a selection program, sooner or later the response to selection becomes negligible (Mather, 1941; Mather and Harrison, 1949; Robertson, 1955; Rasmuson, 1955; Clayton and Robertson, 1957). This type of limited response after continued selection has been observed with respect to the genetic improvement of egg production in the domestic fowl (Lerner and Dempster, 1951; Yamada et al., 1958). A rather unique problem in selecting for egg production is the restricted . . .