Effects of early maturation, layer protein level, and methionine concentration on production performance of brown-egg-type pullets.

Three hundred and sixty 17-week-old Harco Sex Link pullets were transferred to laying cages and received 13 hr of light daily for the first week followed by 15 hr the second and subsequent weeks. A second group of 360 pullets remained in the growing facility on 8 hr of light until 19 weeks of age when the light was increased to 13 hr. At 20 weeks these birds were transferred to the laying facility where they received 15 hr of light daily for the duration of the experiment. A 15% protein grower ration was fed until daily production of each group reached 2%, at which time the diets were changed to either a 17 or 19% protein layer ration, each supplemented with DL-methionine so as to contain .3 or .4% total methionine. Early housed pullets averaged 140.4 days at first egg whereas late housed reached sexual maturity at 149 days. The initial increase in egg production by the early housed pullets was followed by a more rapid decline and overall, from housing to 66 weeks, equivalent egg numbers were produced. The early housed pullets were less efficient than the late housed birds due in part to their larger body mass. The greater percentage of small and medium-sized eggs produced by the early housed birds was not influenced by increasing the concentration of protein or methionine in the layer ration.