It is quite definitely established that the hatching quality of eggs laid during the second laying year is lower than that of the first year. Observation and results reported by Hays and Sanborn (1924), Warren (1934), Funk (1934), and Insko, Lowry and Caldwell (1951) indicate that there can be no doubt that the hatching quality of eggs laid during the first laying year is to a slight but significant degree superior to the hatching quality of those produced during the second year of production.Published data pertaining to changes in hatchability during the first year of production are limited. Insko, Steele and Wightman (1947) reported that first-year embryonic mortality was definitely lower for pullets in progressively older age-groups, and that essentially the same relationship applied to any one week for the respective years. Hays and Talmadge (1949) concluded that, in general, pullets are likely to show a decline in hatchability …