Abstract
An experiment was conducted to test the hypothesis that increasing duration time of heat treatment reduces the concentration of reactive Lys and the standardized ileal digestibility (SID) of Lys and other amino acids (AA) in enzyme-treated soybean meal (ESBM) fed to weanling pigs. Twelve pigs with an average initial body weight of approximately 11.38 ± 1.02 kg had a T-cannula installed in the distal ileum. Pigs were allotted to a replicated 6 × 6 Latin square design with six diets and six periods in each square. There were, therefore, 12 replicate pigs for each diet. The ESBM was divided into four batches, and they were autoclaved at 120 ℃ for 0, 30, 45, or 120 minutes. Five experimental diets were formulated based on each source of ESBM or conventional soybean meal (SBM). These ingredients were the only AA-containing ingredients in each diet. An N-free diet was also used. Data were analyzed using Proc Mixed of SAS and the statistical model included diet as fixed variable, and animal, period, and square as random variables. Linear and quadratic effects of increasing autoclaving time were also analyzed using contrast coefficients. Results indicated that analyzed reactive Lys in ESBM was reduced from 3.07 to 2.29% when duration time of autoclaving was increased. The SID of Lyswas greater in SBM than in non-autoclaved ESBM (P < 0.05), but with the exception of Phe, the SID of other indispensable AA did not differ between SBM and non-autoclaved ESBM (Table 1). The SID of indispensable AA was reduced (linear; P < 0.05) by increasing duration time of autoclaving, but with the exception of Lys, the decrease in the SID of CP and all indispensable AA was greater (quadratic; P < 0.05) or tended to be greater (quadratic; P < 0.10) at 45 or 120 min of autoclaving compared with 30 min of autoclaving. In conclusion, overheating reduced the concentration of all AA and reactive Lys as well as the SID of AA in ESBM fed to weanling pigs. The reduction in the SID of AA was greater when ESBM was autoclaved for more than 30 min.
