Ileal digestibility of the amino acids of soybean meals of different origin in broilers

Abstract

A trial was conducted to determine the apparent (AID) and standardized (SID) ileal digestibility of CP and AA of 22 soybean meals (SBM) from 3 different origins; USA, Brazil (BRA), and Argentina (ARG) in 21-d-old broilers. There were 7 to 8 samples of SBM per origin and 6 replicates (6 chicks each) per each SBM sample. On DM bases, the average CP was 53.5, 55.3, and 52.3% for USA (n = 8), BRA (n = 7), and ARG (n = 7) meals, respectively. The concentration of Lys and Met per unit of protein was highest (P < 0.01) for the USA meal and lowest for the BRA meal with ARG meal being intermediate. The KOH solubility was higher for USA than for BRA and ARG meals (86.5, 82.8, and 80.0%; (P < 0.05) but trypsin inhibitor activity (TIA) was similar for all origins (3.0 mg/g DM). Chicks were fed a commercial corn-soybean meal diet from 1 to 17 d and then, their respective experimental diets, with the SBM tested as the only source of CP (20%), from 18 to 21 d of age. In addition, a N-free diet was used to estimate ileal endogenous losses of the AA in 6 extra replicates. The AID of the 22 SBM samples ranged from 82.9 to 88.0 for CP, from 85.0 to 90.5 for Lys, and from 66.4 to 75.0 for Cys. In general, the AID of CP and of most indispensable AA were similar for USA and BRA SBM meals and for both higher ((P < 0.01) than for ARG meal (i.e., 88.2 and 88.1 vs. 86.7 for Lys and 88.0 and 89.1 vs. 86.6 for Met, respectively). The SID values of the 22 SBM samples ranged from 89.3 to 94.6 for CP, from 90.1 to 94.9 for Lys, and from 78.5 to 85.4 for Cys. The SID values of most indispensable AA were similar for USA and BRA meals and higher for both ((P < 0.05) than for the ARG meal (i.e., 93.0 and 92.7 vs. 91.8 for Lys and 95.6 and 96.9 vs. 94.9 for Met). It is concluded that the ileal digestibility of CP and AA varies considerably among commercial SBM samples. In fact, in this study, USA and BRA SBM had a higher AID and SID than ARG SBM.