Abstract
The purpose of the present study was to examine the effect of dietary Total Phosphorus (TP) on performance, serum P, bone morphometric measurements, phosphorus (P) and calcium (Ca) retention and P excretion of broilers from 3 to 7 weeks of age. The grower diets (3-6 weeks) contained 5.0, 5.5, 6.0 and 6.5 g kg(-1) TP (2.4, 2.9, 3.4 and 3.9 g kg(-1) calculated non-phytate P (npP), respectively); each diet was fed to 6 replicate pens. During finishing period (6-7 weeks), three pens received the same TP level as in the growing period, while the other 3 pens were fed a diet without any inorganic P supplementation (3.8 TP, 1.3 npP g kg(-1)). Decreasing dietary TP from 6.5 to 5.0 g kg(-1) during the growing period or removing dicalcium phosphate completely from the finisher diets had no significant effect on feed intake, body weight gain, breast muscle yield and Feed Conversion Ratio (FCR). Serum P was affected by the amount of P in the diet. Tibiae and femora ash percentages were differed significantly between diets and sex. Phosphorus intake and excretion were functions of the amount of the P in the diet, reducing or omitting P in the diets markedly reduced fecal P. In conclusion, TP levels needed by broilers to maintain growth and feed utilization were less than those needed for maximum tibia ash; TP could be reduced to 5.0 (2.4 npP) g kg(-1) from during the growing period and omitted from the withdrawal diets without adverse effects on live performance or skeletal integrity.