113 Evaluation of high soybean meal diets with inclusion of dietary enzymes on the effect of growth performance and greenhouse gas emissions

Abstract Crossbred gilts n = 48; initial body weight (BW) = 52.55 ± 4.12 kg were used to evaluate the effects of high soybean meal (SBM) inclusion with dietary enzymes on the growth performance, nitrogen balance, and gas emissions of growing pigs. This study consisted of two replicates of 24 gilts placed in individual metabolism stalls. Pigs were randomly assigned to one of six dietary treatments and blocked by BW (4 pigs•treatment-1•replicate-1). Pigs were fed a common diet from d 0 to 12, the experimental diets were fed in two phased (d 12 to 24 and d 24 to 36). The experiment consisted of 3 collection periods, with each period subdivided into two subperiods to collect samples for gas emissions and nutrient balance. Manure samples were collected for 72 h. Twice daily, urine and feces were weighed, and a ratio of the excreta were subsampled to measure gas emissions. Measurement of nutrient digestibility and retention consisted of urine and feces collections over a 72 h-period. The six dietary treatments include: 1) basal control diet (NC) corn-soy diet supplemented with synthetic amino acids, 2) high soybean meal (HSBM) diet (PC) formulated to replace all synthetic lysine, 3) HSBM diet with xylanase (Ronozyme WX 5000; DM; WX), 4) HSBM diet with inclusion of a multi-enzyme additive including hemicellulase and pectinase (Ronozyme VP, DM; VP), 5) HSBM diet with inclusion of xylanase (Ronozyme WX 5000, DM) and multi-enzyme additive including hemicellulase and pectinase (Ronozyme VP, DM; WXVP), and 6) HSBM diet with 1,500 FYT/kg of phytase (HiPhorious, DM; SD). The NC, PC, WX, VP, and WXVP diets contained phytase (HiPhorious, DM Nutritional Products, Parsippany, NJ) to provide 600 phytase units (FTU) per kg of diet and was assumed to release 0.15% available phosphorous. The SD diet contained 1,500 FTU/kg and was assumed to release 0.21% available phosphorous. Additionally, high soybean meal diets within each phase were isocaloric. Data were analyzed as repeated measures in SAS 9.4 (Inst., Cary, NC) with fixed effects of treatment, collection period, and block. Pig was the experimental unit, and results were considered significant at P ≤ 0.05 and a tendency at 0.05 P ≤ 0.10. Pigs fed VP had the greatest average daily gain (ADG) compared with pigs fed SD (P = 0.865; Table 1). Pigs fed VP had the greatest gain to feed ratio (GF) efficiency compared with pigs fed WXVP (P = 0.3544). Manure pH, urine pH and hydrogen sulfide tended to decrease in all treatments from phase 2 to phase 3. Pigs fed PC had the lowest manure pH compared with pigs fed SD (P = 0.0826; Table 2). In conclusion, the feeding of HSBM or adding select enzymes did not alter gas emissions or growth performance metrics.