The supplementation of low-P diets with microbial 6-phytase expressed in Aspergillus oryzae improves P digestibility in sows

Two trials were conducted to evaluate a novel microbial 6-phytase expressed in Aspergillus oryzae (Ronozyme HiPhos; DSM Nutritional Products, Basel, Switzerland) in gestating and lactating sows. In the first trial, 24 sows (Duroc × Landrace; 223 kg BW) were offered, at 16 d of gestation, a low-P control diet (formulated to provide 4.0 g total P/kg; 1.5 g digestible P/kg) supplemented with 0, 500, or 1000 phytase activity (FYT)/kg of phytase. Two weeks later, fresh feces were sampled from all sows and the apparent total tract digestibility of P was measured using TiO(2) as indigestible marker. Phytase supplementation did not (P > 0.10) affect the total tract digestibility of P but reduced (P < 0.05) P concentration in feces (from 14.5 to 12.0 and 12.0 g/kg DM). In the second trial, 32 lactating sows (Duroc × Landrace; 282 kg BW) were used. They were offered, at 7 d of lactation, a low-P control diet (formulated to provide 6.1 g total P/kg; 3 g digestible P/kg) or the same diet supplemented with 500 FYT/kg of phytase. After 2 wk, fresh feces were sampled from all sows and the apparent total tract digestibility of P was measured using TiO(2) as indigestible marker. Phytase supplementation improved (P < 0.001) the apparent total tract digestibility of P from 27.5 to 38.7% and reduced (P < 0.001) P concentration in feces (from 27.5 to 21.4 g/kg DM). In conclusion, the microbial 6-phytase tested increased the apparent total tract digestibility of P in sows and reduced P excretion in feces.