Chemical composition, protein quality and nutritive value of commercial soybean meals produced from beans from different countries: A meta-analytical study

Abstract

Soya bean meal (SBM) is the most important source of protein and indispensable amino acids in non-ruminant diets worldwide. The chemical composition, protein quality and nutritive value of commercial SBM depend on numerous factors, including seed variety, environmental conditions during growing, harvesting and storage of the beans and the procedure used for oil extraction. A meta-analytical approach was conducted to quantify the relation between the country of origin of the beans [Argentina (ARG), Brazil (BRA), USA and India (IND)] and the chemical composition, protein quality and nutritive value of the SBM. The data set used was obtained from 18 published papers from 2002 to 2018 with a total of 1944 samples of SBM. The data were analyzed using a mixed model with country of origin of the beans as a fixed effect and the study as a random effect. Origin of the beans had consistent and significant effects on most of the chemical variables of the corresponding SBM. The BRA SBM had more crude protein (CP), neutral detergent fiber, raffinose and iron but less sucrose, stachyose and K contents than the USA or the ARG SBM (P < 0.05). Per unit of protein, Lys, Met, Thr and Cys concentrations were greater for the USA and ARG meals than for the BRA and IND meals (P < 0.05). Protein dispersibility index (PDI), KOH solubility (KOH) and trypsin inhibitor activity were lower for the BRA and ARG meals than for the USA and IND meals (P < 0.05). Trypsin inhibitor activity was positively related with PDI (r = 0.712; P < 0.001) and KOH (r = 0.886; P < 0.001). Also, a significant relation was observed between PDI and KOH (r = 0.614; P = 0.001). Urease activity, however, was not related to any of the protein quality traits studied. Within the range of CP values (418–500 g/kg) studied a decrease in crude fiber increased (P < 0.01) the CP content of the SBM. In summary, the country of origin of the beans affected the chemical composition and nutritive value of the SBM. Consequently, matrices with different nutrient composition should be used for SBM of different origins in the formulation of diets for non-ruminant animals.