Soybean meal (SBM) is a primary constituent of poultry diets globally due to its protein content and amino acid digestibility. Yet, variations in agronomic conditions, cultivar variety, and processing techniques can alter the digestible amino acid content of SBM. To detect variation in nutritional value, rooster or broiler bioassays with subsequent laboratory analyses can be performed to determine the digestible amino acid content for an individual sample. However, these bioassay determinations are expensive and time-consuming. In contrast, near-infrared reflectance spectroscopy (NIRS) has the potential to enable rapid ingredient analysis, allowing for real-time assessment of nutrient value prior to incorporation in poultry diets. In the current research, calibration curves were designed to assess if NIRS has the capacity to accurately predict the digestible amino acid content of all essential amino acids for solvent-extracted and mechanically- expelled SBM. The cecectomized rooster bioassay was used to determine the digestible amino acid content of over 200 SBM samples. Each SBM sample was uniformly ground before obtaining a complete near-infrared spectral analysis using a Bruker MPA: FT-NIR Spectrometer equipped with OPUS software. Approximately half of the samples were used to construct each calibration curve, while the remaining samples were used to validate each calibration curve. For the validation samples, the average error between NIRS-predicted and bioassay-determined values, measured as root mean square error of prediction (RMSEP), ranged from 0.010 to 0.059 across the essential amino acid validation sets, indicating no significant statistical differences between the bioassay and NIRS-determined values. Moreover, for all essential amino acids, apart from lysine and tryptophan, 100% of the validation samples predicted within ±5% of their bioassay- determined value. For lysine and tryptophan, 98% and 85% of the predicted values deviated by less than ±5% of their bioassay- determined values, respectively. This research indicates that NIRS can be used to accurately predict the digestible amino acid content of all essential amino acids, with a comparable margin of error expected from the bioassay and laboratory analyses for SBM samples used in poultry diets.

Jones, T., C. Hatmaker, C. Chen and A. Davis. 2025. Utilization of near-infrared reflectance spectroscopy to predict the digestible essential amino acid content of mechanically and solvent-extracted soybean meal. 2025 International Poultry Scientific Forum, Abstract M140.