Effect of Delayed Maturity of White Leghorn Chickens on Subsequent Productivity

White Leghorn pullets were subjected to restricted dietary energy (⅔ of voluntary intake) or various daylength treatments during the growing period. Maturity was delayed 3–5 weeks in two experiments by restricting energy intake but only 1–2 weeks by subjecting the pullets to declining daylength compared with increasing or constant daylength. Contrary to previous findings with heavy breeds, there was very little effect of treatment on body weight or carcass fat at maturity. Pullets delayed by restricting energy intake had greater mortality during the growing period but there was no difference in mortality among treatments in the laying period. Pullets delayed in this manner laid more settable eggs, with fewer small and double yolked eggs, and more eggs in the “extra large” and “large” market egg classification than full-fed controls. Efficiency of feed utilization by the restricted pullets was significantly greater than that of the full fed controls during the laying period. Full-fed pullets subjected to declining daylength laid slightly, but not significantly, more settable, more large and extra large, and significantly fewer small eggs than those given increasing or constant daylength.