Growth Performance, Meat Yield, and Economic Responses of Broilers Provided Diets Varying in Amino Acid Density from Thirty-Six to Fifty-Nine Days of Age

Providing broilers diets formulated to a high amino acid density early in life improves subsequent growth performance and meat yield. Diets formulated to high amino acid concentrations beyond 5 wk of age may increase breast meat yield but may not be economically justified. This study examined growth, meat yield, and economic responses of broilers provided diets varying in amino acid density from 36 to 59 d of age. Birds were given a 4-phase feeding program: starter (1 to 17 d), grower (18 to 35 d), withdrawal-1 (WD1; 36 to 47 d), and withdrawal-2 (WD2; 48 to 59 d of age). All birds were fed a common, high amino acid density diet to 35 d of age (HH). Broilers were provided diets characterized as being high (H), moderate (M), or low (L) in amino acid density for the WD1 and WD2 periods. Dietary treatments were HHHH, HHHM, HHHL, HHMM, HHML, and HHLL from d 1 to 59, with H, M, and L representing the diets fed during each of the 4 periods (starter, grower, WD1 and WD2). Cumulative feed conversion was improved when the HHHH feeding regimen was fed, whereas other final live performance measurements were not affected. Decreasing amino acid density (HHLL and HHHL) limited yields of breast fillets, tenders, and total white meat when compared with the HHHH regimen. As amino acid density decreased from HHHH to HHHM, HHMM, and HHML, carcass yield and breast meat yield were not affected. In general, providing the HHHH feeding regimen increased economic gross feeding margin compared with the other dietary treatments.