Effects of Lower Dietary Calcium and Phosphorus on Growth Performance and Bone Mineralization of Broilers

This experiment was carried out to investigate the effects of reduced dietary calcium (Ca) and non-phy-tate-phosphorus (NPP) levels at 2:1 constant ratio on performance, carcase parameters and bone mineralization of Ross-308 broilers. A total of 11400 one-day-old chicks were randomly allocated to five dietary treatments with twelve replicates and were fed starter diets including either recommended (control treatment, T1) or a 6.25% lower level of both Ca and NPP according to breeder's recommendations during starter period (SP). After SP, control treatment (T1) continued to be provided through diets containing 0.87 and 0.78 % Ca for grower (GP) and finisher periods (FP), re-spectively, while 6.25 % reduced group was divided into 4 dietary treatments regarding extent of decrease in Ca and NPP levels and provided by diets containing 0.79;0.65 (T2), 0.79;0.60 (T3), 0.75;0.65 (T4), and 0.75;0.60 (T5) % Ca for GP and FP, respectively. After SP, moderate and even substantial reduction of Ca and NPP significantly decreased feed intake (FI) (quadratic, P<0.05), but obtained similar body weight gain (BWG) and FCR compared to the control (P>0.05). On the other hand, reduced dietary Ca through T1 to T5 significantly decreased the total Ca and NPP intake of broilers (linear and quadratic, P<0.01), and accompanied to significant linear and quadratic relationship between Ca intake and FCR and BWG respectively. It can be concluded that reducing Ca level down to 0.75 and 0.60 % in grower and finisher phase, respectively are possible without compromising the growth performance and bone mineralization of modern broilers.