LAUSR

Abstract An experiment with a 2 × 2-factorial arrangement of treatments was carried out to assess the effect of reduced feed pH and addition of phytase and their interactions on performance, mineral retention (Ca, P, Mg, Zn, Fe and Cu) and bone mineralization. A wheat-based diet with a high phytate-P content and no inorganic P added, or the same diet with either 1.4 % formic acid, 500 FTU C. braakii-derived phytase or both added, were used. Thirty-two piglets, with a mean weight of 21.06 ± 0.83 kg were distributed in eight pens. Individual feed intake was recorded, and all treatments were represented in all pens. The experimental period was 28 days. Performance was recorded, pH in stomach, jejunum and ileum was measured and content from jejunum and ileum was collected for assessment of P digestibility. In addition, feces were collected for total digestibility measurements and left third and fourth metacarpal were analyzed for bone mineralization. No interaction effects between phytase and acid addition were found. Phytase addition increased growth (P=0.046), jejunal P digestibility (P=0.004), total tract digestibility of P (P The experiment confirmed that phytase addition improved P digestibility. However, no increased phytase efficacy was seen with acid addition.