Analysis of published data for standardized ileal digestibility of protein and amino acids in soy proteins fed to pigs

The present work was conducted to determine, via a summary of data from peer-reviewed publications, if differences in the standardized ileal digestibility (SID) of CP and AA in different soy proteins exist when fed to pigs and to determine if the BW of pigs influences the SID of CP and AA. The following ingredients were included in the analysis: dehulled soybean meal (SBM) with 46 to 48% CP (SBM 48%), non-dehulled SBM with a CP concentration of 42 to 44% (SBM 44%), enzyme-treated SBM (ESBM), fermented SBM (FSBM), soy protein concentrate (SPC), and soy protein isolate (SPI). Results indicated that the SID of most AA was not different between SBM 48% and SBM 44%; however, for some AA, greater (P < 0.05) SID values in ESBM, SPC, and SPI were obtained compared with SBM 48%, SBM 44%, and FSBM. The least (P < 0.05) SID of Lys was observed in FSBM, which also had the least Lys-to-CP ratio, indicating that FSBM sometimes is exposed to excessive heat damage during drying of the fermented product. For SBM 48%, it was also possible to analyze the effect of pigs’ BW on the SID of CP and AA. Results indicated that the SID of CP and AA were less (P < 0.05) in pigs of BW less than 20 kg compared with pigs of BW above 20 kg. Therefore, it can be concluded that differences in SID of CP and AA among soy proteins exist and that for SBM 48%, SID values may be less in pigs less than 20 kg than in pigs above 20 kg.