A total number of 288 one-day old Cobb broiler chicks were randomly distributed into 18 equal dietary treatments (each of two replicates). The chicks were assigned to these treatments according to 2*3*3 factorial arrangement to study the effect of the interrelationships between different dietary levels of calcium:available phosphorus ratio (2:1 and 3:1), vitamin A (1500, 15000, and 30000 IU/kg), and vitamin D3 (200, 2000, and 4000 ICU/kg) on performance, carcass quality, tibia ash; Ca and P, liver vit. A, and blood serum Ca and P. The experiment lasted for seven weeks.
Based on the obtained results, the interrelationships between these three factors have led to conclude that Cobb broiler chicks up to 7 weeks of age require levels of Ca:Pa ratio , vit. A and vit. D3 different from those recommended by NRC (1994). The requirements from 0 to 7 weeks of age were proven in this study to be 3:1 Ca:Pa ratio along with 2000 to 4000 ICU vit. D3/kg and 15000 IU vit. A/kg. It is also noteworthy to mention that the requirements for these nutrients were proven to be higher from 0 to 3 weeks of age than from 4-7 weeks of age, since body weight, body weight gain and feed conversion ratio were better at 3:1 Ca:Pa ratio along with 4000 ICU vit. D3/kg and 30000 IU vit.A/kg.