The influence of dietary non-phytate phosphorous (NPP) on growth performance, carcass characteristics, bone quality and serum parameters were investigated to determine the NPP requirement of slow-growing feather-frizzled broilers aged from 1 to 21 days. A total of 480 1-day-old indigenous slow-growing male feather-frizzled broilers were assigned to 1 of 6 treatments with 8 cage replicates of 10 birds each using a completely randomized design. They were fed with corn-soybean meal-based basal diet (containing 0.13 % of NPP) supplemented with 0.00 %, 0.08 %, 0.16 %, 0.24 %, 0.32 %, and 0.40 % of inorganic phosphorus (CaHPO 4 .2 H 2 O), respectively. The experimental diets contained a constant 0.90% calcium. Results showed that body weight gain, feed intake, eviscerated carcass ratio, tibia breaking strength, tibia and toe ash or phosphorous concentrations, femoral strength and serum inorganic phosphorous concentration were affected ( P < 0.010) by dietary NPP level, and showed significant quadratic responses ( P < 0.030) to dietary NPP levels. The estimates of dietary NPP requirements were 0.25–0.36 % based on the best fitted broken-line or quadratic models ( P < 0.029) of the above performance, serum and bone parameters. In conclusion, the NPP requirements would be about 0.25 % to obtain the optimum growth performance and carcass yield, and 0.36 % to meet bone development and P metabolism for such slow-growing feather-frizzled broilers fed a conventional corn-soybean meal diet from 1 to 21 days of age. • Determine non-phytate phosphorus requirement (NPP) for slow-growing feather-frizzled broilers from 1 to 21 days of age. • The optimal NPP ranged from 0.25% for growth and carcass yield, to 0.36 % for bone quality and P metabolism of broilers. • Carcass characteristics might be new consideration of indices.
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