Effects of dietary protease supplementation on in vitro soybean meal protein, dry matter digestibility, and productive performance in starter-to-finisher pigs

Background and Aim: Pig industries are currently facing a crisis in terms of protein and energy costs. Proteases were used to increase protein digestibility and metabolizable energy (ME) in diets. This study evaluated the effects of protease supplementation on in vitro protein digestibility and productive performance in starter-to-finisher pigs. Materials and Methods: A total of 691 starter pigs were randomly allocated into three dietary treatments using a randomized complete block design. Diets were provided in three phases according to body weight (BW): Starter, grower, and finisher phases. Each phase was fed for 30, 60, and 24 days of treatment diets as T1: basal diet and T2 and T3: the basal diet supplemented with 240 ppm protease reduced by 50 kcal/kg ME plus 1% crude protein (CP) and by 100 kcal/kg ME plus 2% CP, respectively. Protease and in vitro protein digestibility were measured. BW and feed intake were recorded to calculate the average daily gain (ADG), average daily feed intake (ADFI), feed-to-gain (F:G), and gain-to-feed (G:F) ratios. Results: There were no significant differences (p > 0.05) in the percentage of in vitro protein digestibility between the groups with and without protease supplementation. In the finisher phase, T2 had lower (p < 0.05) ADFI and F:G than T1 and T3. Overall, T3 had lower (p < 0.05) ADG, ADFI, and F:G than T1 and T2. Conclusion: Protease supplementation significantly affects protein digestibility. Supplementing basal diets with 240 ppm protease reduced ME by 50 kcal/kg and CP by 1% without affecting ADG, ADFI, F:G, and G:F ratios for starter-to- finisher pigs.