Influence of Conditioning and Expansion Characteristics on the Apparent Metabolizable Energy and Standardized Ileal Amino Acid Digestibility of Full-Fat Soybeans for Broilers

SIMPLE SUMMARY: Full-fat soybean (FFSB) is a valuable source of energy and protein for poultry and is obtained by cracking raw soybeans without cooking or oil extraction. However, due to the presence of trypsin inhibitors and lectins, raw FFSB is not used in poultry diets. These anti-nutritional factors are, however, heat-labile, and a proper hydrothermal process will inactivate these factors, eliminating their adverse effects on nutrient utilization and bird performance. The aim of the present study was to investigate the influence of conditioning and expansion characteristics on the apparent metabolizable energy and standardized ileal digestibility (SID) of amino acids (AA) in FFSB for broilers. Based on the results, long-term conditioning at 100 °C for 6 min followed by expansion with 18 kWh/t specific energy input increased the metabolizable energy and SID AA of FFSB. Further increases in conditioning time above 6 min or expansion of specific energy input above 18 kWh/t did not offer any advantages to metabolizable energy and AA digestibility of FFSB. ABSTRACT: This study investigated the influence of short-term and long-term conditioning and expansion on the nitrogen-corrected apparent metabolizable energy (AMEn) and standardized ileal digestibility (SID) of amino acids (AA) in full-fat soybeans (FFSB) for broilers. A batch of raw soybeans was used to manufacture 10 FFSB products (T0 to T9) by applying various combinations of conditioning and expansion. The AMEn and SID AA of FFSB were determined by difference and direct methods, respectively. All heat treatments increased (p < 0.001) the AMEn compared to raw FFSB. The sample subjected to long-term conditioning at 100 °C for 6 min and expansion at 18 kWh/t (T5) supported 3.88 MJ/kg higher AMEn than the raw FFSB. Raw FFSB had the poorest (p < 0.05) AA digestibility. Among the heat-treated samples, the highest (p < 0.05) SID AA was recorded for T5. The results demonstrated that the long-term conditioning of FFSB at 100 °C for 6 min prior to expansion with 18 kWh/t specific energy input enhanced metabolizable energy and SID AA. Further increases in conditioning time from 6 to 9 min or expansion of specific energy input from 18 to 28 kWh/t did not yield additional benefits to energy utilization and AA digestibility of FFSB.