Our objective was to evaluate the effect of crude protein (CP) levels and non-starch polysaccharide (NSP) enzyme on nursery pig performance. 792 mixed sex pigs (6.2 ± 0.12 kg BW) were randomly allotted across six dietary treatments (12 pens/treatment) using a 3×2 factorial. Three base diets, with or without NSPase, were fed in three phases (10, 11 and 21 days, respectively). Base diet and Lys per phase were: 1) 17% low CP with of 1.40, 1.35, 1.30% SID Lys (LCP1.4); 2) 24% high CP, 1.40, 1.35, 1.30% SID Ly (HCP1.4); and 3) 17% CP, 1.20, 1.15, 1.10% SID Lys (LCP1.2). Pig weights and feed disappearance were recorded to calculate ADG, ADFI, and G:F within phase and overall. Pen fecal scores and day 21 fecal dry matter (DM) were evaluated. Data were analyzed with pen as the experimental unit and least square means reported by treatment. Overall and within phase, no diet by enzyme interactions were reported for ADG, ADFI and G:F (P < 0.05). Within diet, HCP1.4 had greater overall ADG compared to LCP1.4 and LCP1.2 (0.42, 0.36, 0.35 kg/d respectively, P < 0.0001). Overall ADFI tended to differ between the LCP1.4, HCP 1.4 and the LCP1.2 treatments (0.60, 0.61 and 0.57 kg/d, respectively, P = 0.066). Overall G:F was greater in the HCP1.4 compared to LCP1.4 and LCP1.2 pigs (0.69, 0.61 and 0.62, respectively, P < 0.0001). Fecal scores and 21-day fecal DM did not differ (P > 0.05) in LCP1.4, HCP1.4 and LCP1.2 pigs (32, 28 and 31% DM, respectively) and with or without enzyme (32 and 29% DM, respectively, P = 0.300).
Overall, compared to no enzyme, enzyme was not different (P > 0.05) for ADG (0.37 vs 0.39 kg/d), ADFI and G:F. In conclusion, low CP diets did not enhance pig performance or alter fecal consistency.