Effects of Supplementation of Protease to Different Nutrient Density of Diets on Growth Performance, Nutrient Digestibility, Blood Profile, Gas Emission, Fecal Microflora in Growing-Finishing Pig

Abstract This study was conducted to investigate the effects of protease supplementation and different nutrient density of diets on growth performance, nutrient digestibility, blood profiles, gas emissions, and fecal microflora in growing-finishing pigs. Crossbred growing pigs (n = 180; [Landrace × Yorkshire] x Duroc) with an initial body weight (BW; 18.74 ± 3.46 kg) were used for 15 weeks. Pigs were randomly assigned to 6 dietary treatments with 6 replicates of 3 pigs per pen in a 3 ⅹ 2 factorial through the following arrangement: Three groups of protease (1, Basal diets; 2, Protease A: 125 mg/kg protease derived from Streptomyces spp; 3, Protease B: 100 mg/kg protease derived from Bacillus licheniformis) at two different nutrient density diets (1; Basal requirement 2; 0.94-0.98% greater than requirement in dietary protein and 50 kcal/kg in energy). Supplementation of protease significantly increased (P < 0.05) BW at weeks 4 and 6. Also, supplementation of protease increased (P < 0.05) ADG at grower periods and weeks 13 to 15. In addition, improvement (P < 0.05) of ADG was observed in pigs fed a high nutrient density diet (HN) compared with basal nutrient density diet (BN) at grower periods and weeks 13 to 15. In apparent total track digestibility (ATTD) of crude protein (CP), there was increased (P < 0.05) in supplementation of protease at weeks 6 and 13. The HN showed increased (P < .0001) ATTD of CP at 6 weeks. BN increased (P < 0.01) ATTD of CP at week 13. Also, there was interaction (P < 0.05) between nutrient density of diets and supplementation of protease. In ATTD of gross energy, supplementation of protease showed increased (P < 0.05) at week 13. The supplementation of protease in diets decreased (P < 0.05) the concentration of blood urea nitrogen (BUN) at week 13. The supplementation of protease in diets decreased (P < 0.05) the emission of NH3 at weeks 6 and 13. Also, H2S was decreased (P < 0.05) due to supplementation of Protease A in diets. At weeks 6 to 9, average daily feed intake showed a tendency to increase (P < 0.10) when the BN diets were fed. Also, during the entire period, feed conversion ratio tended to increase (P < 0.10) when the BN diets were fed. In conclusion, supplementation of protease reduces NH3 in feces and BUN in whole blood by increasing the digestibility of CP and improved growth performance. Also, diets with high nutrient density improved growth performance and nutrient digestibility in grower periods.