Ileal digestibility of crude protein, amino acids, dry matter and phosphorous in pigs fed diets steam conditioned at low and high temperature, expander conditioned or extruder processed

An experiment was designed to determine the effect of hydrothermal treatment (HT) on the coefficient of apparent ileal digestibilities (CAID) of crude protein (CP), amino acids (AA), starch and phosphorous (P) in growing pigs (initial body weight (BW) of 29.5 ± 2.4 kg) fitted with a T-cannula in distal ileum. The mash, based on wheat, fishmeal and soybean meal, was subjected to four HT, giving diets: (1) unconditioned mash as control; (2) low-temperature steam conditioning before pelleting (SC-Low); (3) high-temperature steam conditioning before pelleting (SP-High); (4) expander conditioning before pelleting (EXP); and (5) extruder processing (EXT). The diets were fed to five growing pigs allotted to treatments in a 5 × 5 Latin square design. The HT (average of four HT diets) increased CAID of starch (P=0.001), but did not affect that of DM, CP or P. The CAID for total indispensible AA was improved by HT processing (P=0.041), as were the CAID for Arg (P=0.018), Ile (P=0.044), Lys (P=0.006) and Thr (P=0.013), when compared to the control. For Lys, CAID was greater (P=0.006) for pigs fed the HT diets compared to the control and for the average of EXP and EXT compared to the average of SC-Low and SC-High. For dispensable AA, CAID were not affected by the treatments. In conclusion, HT increased ileal digestibility of starch, total IAA, Arg, Ile, Lys and Thr compared to a control diet fed as mash in growing pigs, with expander conditioning and extruder processing of particular merit for Lys.