Study determined effects of supplementing a corn DDGS-soybean meal (SBM)-based diet with a combination of protease and Bacillus-based direct-fed microbials (DFMDFMs) on the growth performance and apparent total tract digestibility (ATTD) of nutrients of in pigs. Eighty pigs (initial BW = 29.2 kg) housed in 20 pens were fed 2 two diets (10 pens/ per diet), which were a corn DDGS-SBM-based diet without or with a combination of Bacillus subtilis protease at 5,000 U/kg and 3-strain Bacillus-based DFMDFMs at 1.5 × 10 5 E+05 cfuCFU/g. The basal diet contained phytase at 750 FTU/kg and was formulated to meet the NRC (2012) nutrient recommendations for grower-finisher pigs except for NE, Ca, and P contents, which were lower than the recommendations by 0.209 MJ/kg, 0.9 g/kg and 0.9 g/kg, respectively. The diets were fed in 3 phases based on BW: Phase 1 from 30 to 55 kg, Phase 2 from 55 to 75 kg and Phase 3 from 75 to 100 kg. Growth performance was determined by phase, whereas the ATTD of nutrients was determined at the end of Phase 1. Protease and DFMDFMs supplementation increased (P < 0.05) ATTD of gross energy, N nitrogen and P by 8.0%, 10.3%, and 15.5%, respectively, but did not unaffected BW gain and feed intake. In conclusion, adding protease and DFMDFMs to the corn-DDGS-SBM-based diet increased nutrient digestibility but did not unaffected growth performance of pigs, implying that basal diet was not deficient in energy. Thus, basal diets with appropriate low energy values should be developed to optimize utilization of protease and DFMDFMs in diets for pigs.
