The Cause of Lack of Stamina. Dr. A. W. Greenwood. Poultry, October 31, 1936.

Author considers that a pullet which lives for 3 years and produces not less than 140 eggs in her third year possesses “constitutional vigour.”

Neither pullet year records nor pullet breeding have any connection with the inheritance of vigour, since approximately as many persistent fowls were obtained from pullet-bred stock as from 2-year-olds, and the mortality rate was the same.