GUANIDINATED PROTEIN TEST MEALS WITH HIGHER CONCENTRATION OF SOYBEAN TRYPSIN-INHIBITORS INCREASE ILEAL RECOVERIES OF ENDOGENOUS AMINO-ACIDSIN PIGS

The amino acid concentrations of cornstarch-based guanidinated unproce ssed (UGM) and autoclaved (AGM) Nutrisoy (defatted soy flour) protein test meals were compared with the respective unguanidinated Nutrisoy d iets. Endogenous ileal recoveries and true digestibilities of amino ac ids were determined in six growing pigs, fitted with a simple T-cannul a at the distal ileum, fed the guanidinated protein test meals. The UG M and AGM contained 13.4 (high) and 3.0 (low) g/kg dry matter of soybe an trypsin inhibitors (SBTI), respectively. The experiment was a two-p eriod cross-over design with each period lasting 15 d. On d 14 of each period, the pigs were fed the guanidinated test meals followed by 24 h continuous collection of digesta. Concentrations of crude protein an d most of the amino acids in the test meals were higher than in the re spective diets. Apparent ileal amino acid digestibilities of the test meals did not differ (P > 0.05) from reported values for the respectiv e diets and were higher (P < 0.05) by 22.7 (cysteine) to 61.3 (tyrosin e) percentage units for AGM compared with UGM. The ileal recoveries of endogenous amino acids in AGM-fed pigs were lower (P < 0.05) than UGM -fed pigs. Values ranged from -0.10 (arginine) to 0.64 (aspartate + as paragine) and from 0.84 (histidine) to 2.61 (tyrosine) g/kg dry matter intake for AGM-and UGM-fed pigs, respectively. True ileal amino acid digestibilities for AGM were higher (P < 0.05) than UGM with differenc es ranging from 12.7 (tyrosine) to 38.3 (leucine) percentage units. In conclusion, ileal recoveries of endogenous amino acids were increased in pigs fed guanidinated protein test meals with the higher concentra tion of SBTI.