A Feed Serine Protease Improves Broiler Performance and Increases Protein and Energy Digestibility

Effects of a novel serine protease, RONOZYME® ProAct (RPA) on protein solubilisation, hydrolysis and digestibility were tested in a gut simulation model. Furthermore, the effects of RPA (supplemented at 15,000 PROT/kg feed) on growth performance and nutrient digestibility were tested in two in vivo broiler experiments each arranged in a 2×2 factorial design (enzyme x sex in experiment 1 and enzyme x protein level in experiment 2). Each dietary treatment had 12 replicates. In experiment 1, birds were fed 12.7 MJ ME per kg iso-energetic diets in 2 phases. Each diet was fed without or with RPA (C or C+RPA, respectively) to either males or females. In experiment 2, two diets were fed in four treatments. Diet 1 (211 and 200 g CP per kg feed in the starter and grower phases respectively) was fed without or with RPA (NP or NP+RPA, respectively). Diet 2 (200 and 190 g CP per kg feed in the starter and grower phases respectively), was fed without or with RPA (LP or LP+RPA, respectively). At the end of each experiment, eight male birds per treatment were randomly selected and used for ileal digestibility measurements. In vitro, RPA significantly increased the degree of protein hydrolysis, solu-bilisation and digestibility. In males, C+RPA was significantly better than C in WG (2,393 g vs. 2,262 g) and FCR (1.60 vs. 1.65). In females, C+RPA was better than C in FCR (1.37 vs. 1.39) in the starter phase. The FCR of LP+RPA was significantly better than LP. In experiment 1, RPA significantly increased ileal protein (82.8% vs. 76.9%) and energy (77.8% vs. 70.6%) digestibilities. In LP, RPA significantly improved energy digestibility (76.6% vs. 75.5%). These results suggest that RPA can improve broiler performance by enhancing protein and energy digestibility.