Influence of dietary protease supplementation to high and low protein diets on growth performance, nutrient digestibility, blood profiles, and gas emissions in finishing pigs

A total of 160 growing pigs [Duroc × (Landrace × Yorkshire); 54.11 ± 2.81 kg)] were randomly assigned to 1 of 4 treatments in a 2 x 2 factorial design with two different levels of crude protein (CP) (15% or 13%) with or without 0.025 % protease for 10 weeks. Each treatment had 8 replicates with 5 pigs (3 gilts and 2 barrows) per pen. During the overall experimental period, pigs fed a high CP diet supplemented with 0.025% protease showed significantly higher (P < 0.05) daily gain and reduced gain to feed ratio compared to those fed low CP diet without protease. Moreover, at the end of week 10, pigs in the protease-treated group exhibited significantly increased (P < 0.05) BW, apparent total tract digestibility of nitrogen and energy, and significantly reduced ammonia emission. Furthermore, glucose, blood urea nitrogen, and creatinine concentrations were significantly increased (P < 0.05) in pigs fed a high CP diet supplemented with protease. These findings suggest that incorporating 0.025% protease into high CP diets may serve as an effective strategy to enhance the growth and overall performance of pigs while potentially mitigating environmental nitrogen emissions.