Effects of Protease on Growth Performance and Nutrient Digestibility of Growing Pigs

This study was conducted to investigate effects of dietary protease on growth performance and nutrient digestibility of growing pigs. A total of 96 growing pigs (initial BW 31.57 ± 2.97 kg; equal number of barrows and gilts) were randomly assigned to 2 dietary treatments (8 pigs/replicate; 6 replicates/treatment) in a randomized complete block design (BW as a block). Dietary treatments were 1) a diet based on corn, soybean meal, and wheat (CON) and 2) CON + 0.02% protease (PRO). The protease used in this study was a commercial protease product (Ronozyme® ProAct, DSM Nutritional Products, Kaiseraugst, Switzerland) containing 75,000 protease units/g derived from Bacillus licheniformis. Pigs were fed respective dietary treatments for 6 weeks. For the last week of the experimental period, pigs were fed respective dietary treatments containing 0.2% chromic oxide as an indigestible marker. Fecal samples from two randomly selected pigs in each pen were collected daily by rectal palpation for the last 3 days after the 4-day adjustment period. Measurements were growth performances and digestibility of dry matter, nitrogen, and energy by an index method. Data were analyzed using the PROC GLM procedure of SAS. The statistical model for every measurement included dietary effect and BW as a covariate. Pigs fed PRO had greater ADG (0.944 vs. 0.877 kg/d; P < 0.05) and G:F (0.450 vs. 0.401 kg/kg; P < 0.05) than those fed CON. However, no difference was found in ADFI between CON and PRO (2.16 vs. 2.10 kg/d). In addition, there were no differences in apparent total tract digestibility of dry matter (74.90 vs. 79.63%), nitrogen (69.62 vs. 76.23%), and energy (74.04 vs. 79.14%) between CON and PRO. In conclusion, addition of protease in grower diets improved growth performance and did not affect nutrient digestibility in growing pigs.