University of Arkansas, Fayetteville Division of Agriculture


An experiment was conducted to evaluate the efficacy of a nutrition program referred to as “phase-feeding” (PF) over the first 6 weeks posthatching. Diets were formulated using amino acid recommendations from the National Research Council (NRC) (1994) or from linear regression equations generated from best estimates of lysine (Lys), sulfur amino acid (SAA), and threonine (Thr) requirements. Regression equations were used to predict weekly Lys, SAA, and Thr requirements for use in a PF regimen that involved lowering amino acid levels following each respective week of the experiment, resulting in six diets fed over the 6-week period. Over the entire experiment (0 to 6 weeks), birds fed a PF regimen throughout had an increased (P < 0.05) weight gain, feed intake, and weight gain per unit of digestible Thr intake relative to birds fed NRC requirements throughout. No differences (P < 0.05) in carcass yield or abdominal fat percentage were noted. These data suggest that PF during the first 6 weeks of age can support growth and carcass yield comparable to diets formulated using NRC requirements. Dietary cost analysis indicates that substantial economic benefits may result from the use of PF during the starter and grower periods.