An experiment was conducted to study the influence of the origin of the beans on the chemical composition, protein quality, and nutritive value of the corresponding soybean meals (SBM). In addition, the in vitro protein digestibility of the meals was determined using a two-step test that simulated the digestive processes occurring in the gastrointestinal tract of the chick. A total of 160 commercial samples of SBM from South Africa (SAF), Argentina (ARG), Brazil (BRA), and USA, in equal numbers, were collected by specialized quality control personnel. Samples from SAF were collected in the country of origin, whereas the samples from the other 3 origins were obtained from crushing plants in different European locations or at the arrival of the vessels to European ports. The data were analyzed as a completely randomized design using the GLM procedure of SAS with country of origin of the SBM as main effect. When significant differences were detected, the Tukey test was used to separate treatments means. On 88% DM bases, the BRA meals had more crude protein and crude fiber contents than all the other meals (P<0.01). The highest ether extract (EE), sucrose, and phosphorus content were observed for the SAF meals (P<0.01). The amino acid (AA) profile of the SBM varied with the origin of the beans, with the SAF and USA meals having more Lys and total sulfur AA per unit of protein than the South American SBM (P<0.01). In general, all protein quality indicators [urease activity (UA), protein dispersibility index (PDI), KOH solubility (KOH), and trypsin inhibitor activity (TIA)] were lower for the ARG meals than for all the other meals (P<0.01). The in vitro protein digestibility, determined in 30 SBM samples per origin after 3 h of incubation, was higher for the SAF than for the ARG and BRA meals with the USA meals being intermediate (P<0.01). Independently of SBM origin, in vitro protein digestibility values were highly correlated with TIA (r = 0.442; P < 0.001) and KOH (r = 0.234; P < 0.05) but not with UA or PDI. Based on accepted prediction equations, the AMEn, content of the SBM was higher (P < 0.001) for the SAF meals than for the South American meals with the USA meals being intermediate.
It is concluded that the origin of the beans affects the chemical composition, protein quality, and in vitro protein digestibility of the SBM. Because of their higher EE and sucrose content, the AMEn of the SBM was greater for the SAF meals than for the USA meals and greater for both than for the South American meals, although the differences not always were significant. In summary, feed mill managers should use different matrices to estimate the chemical composition and nutritive value of SBM of different origins.