Efficacy of xylanase and β-glucanase blend in mixed grains and grain co-products-based diets for fattening pigs

The efficacy of xylanase and β-glucanase and (XB) enzymes blend (Axtra® XB) on the growth performance and fecal digestibility in fattening pigs fed mixed grains and grain co-products-based diets was investigated. Diets were: (1) control, met the National Research Council (NRC) (1998) requirements (except for DE, which was 8% lower), (2) control plus 50 g  XB t−1, and (3) control plus 200 g XB t−1. The target enzyme activities in diet 2 were 610 and 76 U kg−1 feed for xylanase and β-glucanase, respectively and corresponding activities for diet 3 were 2440 and 304 U kg−1 feed. All diets had phytase (Phyzyme® XP, 500 FTU kg−1 feed) and acid insoluble ash as digestibility marker. The experiment had two phases, grower phase (from ∼21.8 to ∼55 kg body weight) and finisher phase (from ∼55 to ∼90 kg BW). Forty-eight growing pigs were assigned within gender to pens (n=2 pigs per pen) to give 8 pens per diet. The pigs had free access to feed and water and feed intake and BW were measured bi-weekly and duration (number of days) the pigs took in each phase was recorded to determined average daily feed intake (ADFI), average daily gain (ADG) and gain efficiency (GF). Feces were sampled in the last week of the grower phase for determination of the coefficients of apparent total tract digestibility (CATTD). An interaction (P=0.01) between diet and sex was observed for ADG during the grower phase and for the number of days it took to reach 90 kg BW. In this context, XB linearly increased ADG (P=0.002) and decreased (P=0.01) duration to 90 kg in gilts. In the grower phase, XB quadratically (P=0.041) increased ADFI in both sexes. However, in the finishing phase and in the entire experiment, the barrows had higher (P<0.05) ADFI and ADG than the gilts and took less (P=0.003) days to reach 90 kg. Supplemental XB linearly increased (P<0.05) CATTD of DM, GE and N in both sexes. The current study demonstrates that xylanase and β-glucanase blend in an energy-deficient, mixed grains and grains co-products-based diet linearly improved growth performance in a diet balanced for growing gilts linked with increased digestibility. However, it is noteworthy that the higher digestibility from the XB supplementation observed in barrows was not reflected in better growth performance perhaps suggesting higher feed intake might have compensated for the reduced energy in the control diet.