The effect of protease and xylanase enzymes on growth performance and nutrient digestibility in finisher pigs

Two 2 × 2 factorial experiments were conducted to investigate the interaction between xylanase (0 vs. 200 mg/kg) and protease (0 vs. 200 mg/kg) enzyme supplementation on growth performance (Exp. 1) and coefficient of ileal and total tract apparent digestibility in grower-finisher pigs (Exp. 2). One hundred and twenty-eight individual fed pigs (BW = 34.2 kg; n = 32) were assigned to 1 of 4 dietary treatments: basal diet (T1), T1 + xylanase enzyme (T2), T1 + protease enzyme (T3), or T1 + xylanase + protease enzymes (T4). The pigs offered diets containing protease enzymes had reduced daily gain (0.795 vs. 0.840 kg/d; P < 0.05) and final body weight (96.4 vs. 99.1 kg; P < 0.05) compared to pigs offered diets without protease enzymes. Pigs offered xylanase-supplemented diets had reduced daily gain (0.787 vs. 0.848 kg/d; P < 0.05) compared to pigs offered diets without xylanase enzymes. In Exp. 2, the nutrient digestibility experiment consisted of 24 intact male pigs (n = 6; BW = 78 kg), offered identical diets to that offered in Exp. 1. Following the fecal collections, the pigs were slaughtered and digesta samples were taken from the ileum in order to measure apparent ileal N and GE digestibilities. Pigs offered diets supplemented with protease had increased coefficients of ileal digestibility of N compared to pigs offered diets without protease supplementation (0.583 vs. 0.449; P < 0.05). There was a xylanase × protease interaction (P < 0.05) on the apparent ileal digestibility of GE. Pigs offered diets containing protease only had increased apparent ileal digestibility of GE compared to basal fed pigs; however, the ileal digestibility of GE decreased when protease was combined with xylanase. Neither xylanase nor protease enzymes had any effect on total tract digestibility of GE or N. In conclusion, xylanase and protease enzyme supplementation had no positive effects on grower-finisher pig performance.