PSLBII-30 The effect of different soybean meal batches and protease supplementation on nutrient utilization by broiler chickens

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Abstract Soybean meal (SBM) is the major protein source in broiler chicken diets. However, the thermal processing of SBM may have an impact on its protein quality, reducing its solubility when over-processed. In this context, the use of exogenous protease may reduce the negative effects that the over-processing of SBM may have on protein digestibility in broiler chickens. The present study investigated two batches of SBM in broiler chicken diets supplemented or not with protease. One-d-old male Cobb 500 (n = 360) were randomly distributed in a 2 x 2 factorial arrangement (SBM batches: A and B; Protease inclusion: 0 and 50 g/t of diet). SBM protein quality was evaluated through crude protein (CP), KOH solubility, and urease activity test (UA) in batches A and B. Scanning electron microscopy was used to visualize the structural organization of particles from SBM A and B. On d 26, ileal digesta content was collected from 6 broiler chickens that were euthanized to determine the apparent ileal digestibility (AID) of dry matter (DM), crude protein (CP), and ileal digestible energy (IDE). Data obtained were submitted to ANOVA and means were compared by Tukey test with a significance declared of 5% using the GLM procedure on R Software. Protein quality assessment demonstrated KOH solubility of 85% and 75% for SBM from batches A and B, respectively. For UA analysis, SBM batch A presented 0.09 and batch B of 0.01 mg N/g (Table 1). Microscopy images emphasized visual differences in particles from batches A and B. In SBM particles from batch A, disorganized cluster structures and asymmetric pores were observed, whereas in the SBM particles from batch B, insignificant pores and large cluster aggregates were visualized in a denser structure (Figure 1). The SBM batch B presented decreased AID of DM, CP, and IDE (P < 0.05). Protease supplementation improved the AID of CP (P < 0.05) in broilers at 26 d of age, regardless of SBM batches, but no effect was observed for DM and IDE (P > 0.05; Table 2). In conclusion, SBM from batch A had greater values of KOH solubility and UA, suggesting an appropriate thermal process, and ensuring protein quality, which is demonstrated through improvement in nutrient utilization by broiler chickens. The use of 50 g of exogenous protease per t of diet improved the ileal digestibility of CP, regardless of SBM batches.