The effect of wheat phosphorus content and supplemental enzymes on digestibility and growth performance of weaner pigs

A 2 × 4 factorial experiment was conducted with the respective factors being wheat phosphorus (P) content (low-P variety: 2.52 g/kg DM, and high-P variety: 3.76 g/kg DM) and enzyme supplementation (no enzyme, xylanase, phytase, and xylanase plus phytase). The enzymes were xylanase (Porzyme® 9300, minimum activity 4000 U/g endo-1,4-β-xylanase) and phytase (Phyzyme™ XP, activity 4100 U/g phytase). Eighty male weaner pigs (Landrace × Large White, 5.4 ± 0.07 kg) were fed an identical pre-trial diet for 1 week and then received their respective experimental diet for 3 weeks. All diets contained 610 g wheat/kg and similar concentrations of calculated digestible energy (14.2 MJ/kg), available lysine (0.78 g/MJ DE), available P (3.2 g/kg) and Ca:P (1.46:1). Collection of faeces was made for three consecutive days from day 14 for determination of digestibility, using titanium dioxide as an indigestible marker. The main effect of wheat P content on the coefficient of total tract apparent digestibility (CTTAD) of DM, CP, energy, P and Ca was not significant (P > 0.05). Enzyme supplementation, as a main effect, influenced the CTTAD of DM (P < 0.01) and energy (P < 0.01), such that xylanase plus phytase decreased their CTTAD. Xylanase plus phytase improved the CTTAD of P and Ca in the high-P wheat variety diet but not in the low-P wheat variety diet (interaction P < 0.001 and P < 0.05, respectively). For performance, significant improvements (P < 0.05) were only seen in week 1 of the feeding trial. In summary, the wheats used in this study responded differently to xylanase and phytase, and a synergistic effect of xylanase plus phytase supplementation was not significant for either digestibility or pig performance.