Abstract
Nine consecutive flocks of SCWL pullets were started at 13-wk intervals and housed in individual laying cages. Beginning with the fourth flock, four different age groups of hens from the same genetic line were housed in the same environment and fed the same experimental diets to test the hypothesis that the methionine and total sulfur amino acid (TSAA) requirements of hens vary with age and stage of production. For the last eight weeks of each 13-wk period, estimates were made of methionine and TSAA requirements for maximum egg production, egg weight, and egg mass. Results indicate that the methionine and TSAA requirements do not diminish with age and stage of production. Requirements were greater for the middle and final quarters of production than for the initial quarter. Peak daily requirements for methionine were 384, 380, and 402 mg/day for egg production, egg weight, and egg mass, respectively. These results indicate that the application of a phase feeding program based upon a reduction in protein or amino acid requirement as hens age has no scientific basis. Adjustments should be made in dietary amino acid levels to compensate for changes in daily feed intake as influenced by environmental changes, feather covering, or other factors in order to maintain a constant amino acid intake, but adjustment based on age or stage of production is not justified.
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