Effects and interaction of dietary calcium and nonphytate phosphorus for slow-growing yellow-feathered broilers between 56 and 84 d of age

This experiment investigated the effect and interaction of dietary calcium (Ca) and nonphytate phosphorus (NPP) on growth performance, tibial characteristics, carcass traits, and meat quality for slow-growing yellow-feathered broilers during 56 to 84 d of age. A 3 × 3 factorial arrangement was used, and 720 56-day-old broilers were randomly divided into 9 groups and fed with diets containing different levels of Ca (0.70, 0.80, 0.90%) and NPP (0.30, 0.35, 0.40%) for 28 d. The dietary Ca level affected the ADFI of yellow-feathered broilers (P < 0.05), and the ADFI of birds fed with 0.90% Ca was increased (P < 0.05) compared with that of birds fed with 0.70% Ca. Birds received 0.35 or 0.40% NPP had higher final BW, ADG, and ADFI than those fed with 0.30% NPP (P < 0.05). The tibial diameter of birds fed with 0.80% Ca was increased compared with that of other groups (P < 0.05). The dietary NPP level did not affect tibial characteristics (P > 0.05). The dietary Ca level did not affect carcass traits (P > 0.05). When broilers were fed with 0.30% P, the semieviscerated percentage was increased compared with birds fed with 0.40% NPP (P < 0.05). The dietary Ca level had significant effects on the L∗ value and shear force of the breast muscle, and the dietary NPP level affected the L∗ value and drip loss of the breast muscle (P < 0.05). Furthermore, the effect of interaction between the level of Ca and NPP was observed on the L∗ and a∗ value (P < 0.05). In conclusion, dietary Ca had influence on performance, tibial characteristics, and meat quality of yellow-feathered broilers, and dietary NPP affected performance, tibial characteristics, and carcass traits. Furthermore, the effect of interaction between the dietary Ca and NPP level was observed on carcass traits and meat quality. Considering all aforementioned indicators, 0.80% Ca and 0.35% NPP were recommended for slow-growing yellow-feathered broilers aged 57 to 84 d of age.