The effect of reduced feed pH, phytase addition and their interaction on mineral utilization in pigs

An experiment with a 2 x 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<0.001) and Ca (P<0.001) and bone mineralization (P<0.001). Acid addition improved growth (P=0.002) and FCR (P=0.033) in addition to total tract digestibility of Mg (P=0.04), Fe (P<0.001) and Ca (P=0.001). The experiment confirmed that phytase addition improved P digestibility. However, no increased phytase efficacy was seen with acid addition.

Automated summary

The experiment showed that adding phytase can improve phosphorus digestibility, but adding acid does not increase the efficacy of phytase. The addition of phytase can increase growth rate and phosphorus digestibility, while the addition of acid can improve growth rate and feed conversion rate.