Coated compound proteases improve nitrogen utilization by decreasing manure nitrogen output for growing pigs fed sorghum soybean meal based diets

Abstract The objective of this study was to determine the effects of coated compound proteases on performance, apparent total tract digestibility (ATTD) of crude protein (CP), serum urea nitrogen (SUN) content and manure nitrogen (N) output for growing pigs fed sorghum soybean meal based diets. Forty crossbred pigs (Duroc × Landrace × Yorkshire) with initial body weight of 23.4 ± 1.2 kg were allotted to 2 diets with 5 replicate pens per treatment (2 barrows and 2 gilts per pen) according to sex and weight in a randomized complete block design. The 2 diets were sorghum soybean meal based diets supplemented with or without 250 mg/kg of coated compound proteases. The experiment period lasting for 70 d was divided into 2 stages including phase 1 (d 1–35) and phase 2 (d 36–70). Proteases had no significant effects on average daily feed intake (ADFI) or average daily gain (ADG), and tended to increase feed conversion efficiency (ADG/ADFI) during phase 1 ( P  = 0.06), phase 2 ( P  = 0.09) or overall ( P  = 0.08) compared with control. The ATTD of dry matter, organic matter and gross energy tended to be greater on d 35 ( P  = 0.08), and was greater on d 70 ( P   0.05) in diets supplemented with proteases than control. Proteases increased the ATTD of CP by more than 8% ( P   0.05), and decreased the faecal N excretion per weight gain by more than 10% ( P   0.05) regardless of the experiment stages. The SUN concentration tended to be reduced by the protease supplementation on d 35 ( P  = 0.09) or d 70 ( P  = 0.06). Accordingly, coated compound proteases could improve N utilization by decreasing manure N output for growing pigs fed sorghum soybean meal based diets.