Supplementation of protease and different nutrient density diets in growing-finishing pigs

Sehyun Park, Jihwan Lee, Seokman Hong, Won Yun, Hanjin Oh, Dongcheol Song, Seyeon Chang, Jaewoon An, Hyunah Cho, Kyeongho Jeon, Jinho Cho*
Author Information & Copyright
1Chungbuk National University, Cheongju 28644, Korea.
*Corresponding Author: Cho Jinho, Chungbuk National University, Cheongju 28644, Korea. E-mail:

© Copyright 2023 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study was conducted to investigate the effects of protease supplementation and different nutrient density of diets in growing-finishing pigs. A total of one hundred-eight crossbred growing pigs ([Landrace × Yorkshire] × Duroc) with an initial body weight (BW; 18.74 ± 3.46 kg) were used for 15 weeks. Pigs were randomly assigned to six dietary treatments with 6 replicates of 3 pigs per pen in a 3 × 2 factorial through the following arrangement: Three groups of protease (1, Basal diets; 2, Protease A: 125 mg/kg protease derived from <italic>Streptomyces </italic>sps; 3, Protease B: 100 mg/kg protease derived from <italic>Bacillus licheniformis</italic>) at two different nutrient density diets (1, Basal requirement; 2, 0.94-0.98% higher than requirement in dietary protein and 50 kcal/kg in energy). High nutrient (HN) diets showed higher average daily gain (ADG) (<italic>p </italic>&lt; 0.05) and apparent total tract digestibility (ATTD) of CP (<italic>p</italic> &lt; .0001) compared to basal nutrient (BN) diets during growing periods. Supplementation of protease showed higher BW (<italic>p </italic>&lt; 0.05) and ADG (<italic>p </italic>&lt; 0.05) compared to non-supplementation of protease during growing periods. Also, supplementation of protease showed higher ATTD of crude protein (CP) (<italic>p </italic>&lt; 0.01), ATTD of gross energy (<italic>p </italic>&lt; 0.05) and decreased blood urea nitrogen (BUN) level (<italic>p </italic>= 0.001) compared to non-supplementation of protease during finishing periods. Pigs which fed the protease showed decreased ammonia (NH<sub>3</sub>) emissions (<italic>p </italic>&lt; 0.05) during experiment periods and decreased hydrogen sulfide (H<sub>2</sub>S) emissions (<italic>p </italic>&lt; 0.01) during finishing periods. Interactions between nutrient density and protease were observed, which decreased the feed conversion ratio (<italic>p </italic>&lt; 0.05) in HN diets without protease compared to BN diets without protease during weeks 4 to 6. Also, interaction between nutrient density and protease was observed, which resulted in improved ATTD of CP (<italic>p </italic>&lt; 0.01) in response to PTA supplementation with HN diets during the finishing period. In conclusion, supplementation of protease reduces NH<sub>3 </sub>in feces and BUN in whole blood by increasing the digestibility of CP and improves growth performance. Also, diets with high nutrient density improved growth performance and nutrient digestibility in growing periods.

Keywords: Nutrient density; Protease; Growing pigs; Finishing pigs