Phase-feeding supports maximum growth performance of broiler chicks from forty-three to seventy-one days of age

Phase-feeding(PF) was tested to evaluate its efficacy compared with NRC rec ommendations for broilers. Two modified PF regimens were also tested that i nvolved lowering amino acid requirements predicted by PF linear regression equations by 10% (PF10) and increasing the slope of the linear regression e quations by 15% (PF15). Experimental diets were fed from 43 to 71 d. Broile rs fed the NRC regimen were given a single diet throughout the experiment, whereas PF, PF10, and PF15 were tested with a series of four diets (43 to 5 0 d, 50 to 57 d, 57 to 64 d, and 64 to 71 d). At 71 d, no differences (P < 0.05) in weight gain, feed intake, or feed efficiency were observed among t reatments. Intake of crude protein, digestible lysine, sulfur amino acids ( SAA), and threonine were decreased (P < 0.05) by PF, PF10, and PF15 relativ e to that of broilers fed the NRC diet. Gain per unit digestible lysine and threonine intake were increased (P < 0.05) by PF, PF10, and PF15, and gain per unit digestible SAA intake was increased (P < 0.05) by PF10 and PF15 r elative to broilers fed the NRC diet. No differences (P > 0.05) were observ ed in carcass, breast, wing, or leg yield, but abdominal fat was increased (P < 0.05) by the PF10 regimen relative to that of broilers fed the NRC die t. Economic analysis indicated that PF and PF10 may lower the cost of feed consumed and the cost per unit weight gain or breast yield relative to broi lers fed the NRC diet.