Methods of Delaying Sexual Maturity of Pullets

In three experiments, delay of sexual maturity of broiler breeder pullets has consistently resulted in increased production of total eggs, increased percentage of settable eggs, and increased average egg weight. When the delay was accomplished by restricting energy intake to about two thirds of voluntary consumption the pullets were considerably leaner at time of maturity. Birds delayed in reaching maturity by the use of declining daylength were fatter at time of maturity, but this did not appear to be detrimental in terms of egg production or percent settable eggs. In periods of extremely hot weather, however, greater mortality occurred in those groups which were more obese at time of maturity. When restricted energy and declining daylength were both imposed the beneficial effects on productivity were additive. Energy restriction was accomplished equally well by diets of relatively high or low energy density when feed intake was restricted to permit two-thirds of voluntary energy intake of a control group. The skip-a-day program, in which the entire ration was restricted to approximately two-thirds of the control group, proved to be an equally satisfactory method of delaying maturity. The low-lysine or low-protein programs did not delay maturity appreciably or improve egg production over full-fed controls when all groups received constant daylength.