Bone mineralization and phosphorus kinetics in chicks fed with non defluorinated phosphates

To measure mineralization and phosphorus kinetics in bone tissue of chicks fed with non-defluorinated sedimentary phosphates, 280 one day old chicks were distributed in 7 groups, with 4 replications of 10 birds each, in a randomized design. Each group received one of the following phosphates: Riecito (RIO), Lizardo (LIZ), Monte Fresco (MON), Navay (NAV), Chiguard (CHI) and Jaji (JAJ), or a high purity dicalcium phosphate (DIC) as control. Birds were fed the different phosphates in the last week of a three week experimental period. The diets were isocaloric (3,100kcal ME/kg), isoproteic (24% CP), with equal Ca (1%). Sedimentary phosphates added 0.20%P to a basal diet with 0.41%P Body weight and feed intake were recorded. Birds were then dosed orally with 10 mu Ci Of P-32 (Na2HPO) for kinetic studies. In and out bone P-32 movement was measured, relating specific activity with time after dosing. At three weeks of age, birds had similar body weight but different bone mineralization values. Ash and P content were greater (P<0.05) for DIC, followed by LIZ and RIO, lower (P<0.05) for CHIG, MON, NAV and JAJ. The highest P-32 level was reached at 5h postdosification with specific activity values of 0.041, 0.047, 0.043, 0.061, 0.069, 0.064 and 0.067 for DIC, RIO, LIZ, CHI, JAJ, MON and NAV with no differences between DIC, LIZ and RIO, these being higher (P<0.05) than CHI, MON, NAV and JAJ. Kinetics of 32P leaving the bone was faster for DICAL with t(1/2) of 16.34h, while this was lower for the sedimentary phosphates, with values of 22.50, 20.75, 21.26, 23.31, 21.00 and 24.67h, respectively for RIO, LIZ, CHI, JAJ, MON and NAV and relative average biological values (100% DIC) were 74.0, 73.3, 53.5, 576.2, and 63.7%.