Abstract: 【Objective】Soybean meal is the main raw material of feed. However, various anti-nutritional factors (ANF) in soybean meal hinder the digestion, absorption and utilization for nutrients, which would have negative effects on animal growth and health. Studies have shown that soybean meal fermented by microorganism could decrease the undesirable effect of ANF. While, fermentation strains, soybean species, and manufacturers may have an effect in fermentation process. Moreover, seldom reports referred to the levels of ANF in soybean meal and fermented soybean meal. Based on this, 65 batches of available soybean meal and 54 batches of fermented soybean meal were collected in this study, followed by analysis of 6 kinds of ANF, including glycinin, β-conglycinin, trypsin inhibitors, raffinose, stachyose and urease, in order to investigate the actual levels of ANF in soybean meal and fermented soybean meal.【Method】In this study, glycinin, β-conglycinin and trypsin inhibitors were analyzed by Enzyme-link Immunosorbent Assay (ELISA) method. Experimental procedures were conducted according to instructions which were sample pretreatment, plus, washing, adding enzymatic reagent, color reaction, and termination. The analysis method of raffinose and stachyose was HPLC after extracted by microwave. Analysis of urease refers to GB/T 8622-2006, and titration was utilized for analysis of urease activity.【Result】The average concentration of glycinin in soybean meal (129.3 mg·g^-1) is 57.7% higher than fermented soybean meal (54.7 mg·g^-1). The percentile method was used for analysis. The normal values in soybean meal and fermented soybean were 58.9-177.3 mg·g^-1 and ND (Not Detected)-109.4 mg·g^-1, respectively. Moreover, the fermented soybean meal (37.6 mg·g^-1) is 63.2% lower than the concentration of β-conglycinin in soybean meal (102.2 mg·g^-1). The normal values in soybean meal and fermented soybean were 42.8-147.2 mg·g^-1 and ND-61.8 mg·g^-1, respectively. The average concentration of trypsin inhibitors in soybean meal (18.4 mg·g^-1) is 59.1% higher than fermented soybean meal (7.5 mg·g^-1). In addition, the normal values of trypsin inhibitor in soybean meal and fermented soybean meal were ND-28.9 mg·g^-1 and ND-9.9 mg·g^-1. The average concentration of raffinose in soybean meal and fermented soybean meal were 11.02 mg·g^-1 and 1.93 mg·g^-1, with the former is 80% higher. The normal values of raffinose in soybean meal and fermented soybean meal were ND-13.79 mg·g^-1 and ND-4.65 mg·g^-1. The average value of stachyose average in soybean meal (29.70 mg·g^-1) is higher than in fermented soybean meal (5.19 mg·g^-1). The normal values of stachyose are ND-33.29 mg·g^-1, ND-11.58 mg·g^-1, respectively. The normal values of urease in soybean meal was in the range of ND to 0.40 U·g^-1, while the activity value of urease of fermented soybean meal was under the detection limit.  It was concluded that the concentrations of ANF in fermented soybean meal have decreased differently compared with soybean meal.【Conclusion】This research provided data support for further optimization of feed processing, and could act as a guide for breeding companies to choose higher quality of soybean meal and fermented soybean meal as feed raw materials.

Key words: soybean meal, fermented soybean meal, AFN