Growth performance and nitrogen excretion of broilers using a phase-feeding approach from twenty-one to sixty-three days of age.

Two experiments were conducted to assess effects of phase-feeding (PF) on broilers from 21 to 63 d. Experiment 1 evaluated the impact of PF on growth performance, whereas experiment 2 assessed the effects of PF on CP intake and nitrogen excretion. Diets were formulated using recommendations from NRC or linear regression equations. Two PF treatments were prepared: standard (PF) and low (PF10), in which predicted Lys, sulfur amino acid, and Thr recommendations were reduced by 10%. For PF and PF10, 2 diets (high-nutrient and low-nutrient density) were blended in variable quantities to produce rations matching predicted requirements. An NRC grower and finisher diet or a series of PF and PF10 diets that were switched every other day were fed. In experiment 1, weight gain and feed efficiency were improved (P < 0.05) by PF10 relative to broilers fed the NRC-based diet. Crude protein intake was reduced (P < 0.05) by PF10 relative to broilers fed NRC and PF diets. No differences (P > 0.05) in percentage carcass composition were observed when broilers were fed PF or PF10 diets. Significant reductions (P < 0.05) in dollars per kilogram of weight gain were noted with PF regimens. In experiment 2, PF and PF10 diets reduced (P < 0.05) CP intake and nitrogen excretion from 43 to 63 d. Results indicate that PF regimens may substantially reduce dietary costs and may have environmental benefits.