Effect of microbial phytase and 1,25-dihydroxycholecalciferol on dietary copper utilization in chicks

Bile Cu accumulation in Cu-depleted chicks fed Cu concentrations between .56 and 1.56 mg Cu/kg (0, .5, or 1 mg supplemental Cu/kg) was used to investigate the effect of microbial phytase at 600 U/kg and 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] at 10 micrograms/kg on Cu bioavailability from dehulled soybean meal (SBM) and cottonseed meal (CSM). The bioavailability of Cu (relative to CuSO4.5H2O, which was set at 100%) in SBM and CSM was 43 and 39%, respectively. Phytase addition (600 U/kg diet) decreased Cu bioavailability in SBM to 21%, but did not affect that in CSM (34%). Copper bioavailability in SBM was not affected by addition of 1,25-(OH)2D3 (10 micrograms/kg diet), but that in CSM was nearly doubled by 1,25-(OH)2D3 supplementation.