Plant-based feedstuffs may have limitations in nutrient digestibility and nutritional value for pigs that might be ameliorated using heat processing technologies. Thus, the main objective was to evaluate the effect of steam-pelleting or extrusion on digestibility of starch, crude protein (CP), amino acids (AA), and gross energy (GE) of the two contrasting ingredients barley and faba bean in growing pigs. Barley and faba bean ingredients were ground (2.8-mm hammer mill screen), and a portion of each ingredient meal was either steam-pelleted or extruded. Subsequently, the heat-processed ingredients were re-ground. Seven crossbred ileal-cannulated barrows (54.3 ± 3.9 kg) were fed 6 diets containing 95.6% of each of the test ingredients and an N-free diet in a 7 × 7 Latin square. Pigs were fed diets at 2.8 × maintenance digestible energy (DE) during seven 9-d periods consisting sequentially of a 5-d adaptation, 2-d collection of feces, and 2-d collection of digesta. Data were analyzed as a 2 × 3 factorial arrangement. Meal barley contained (as is) 47% starch, 11% CP, 4.8% acid-detergent fiber (ADF), and 2.0% acid-hydrolyzed ether extract (AEE). Meal faba bean contained (as is) 28% starch, 27% CP, 8.6% ADF, and 1.9% AEE. Meal barley had greater (P < 0.05) apparent ileal digestibility (AID) of starch but generally lower (P < 0.05) AID and standardized ileal digestibility (SID) of AA than meal faba bean. Heat processing interacted (P < 0.05) with barley and faba bean on diet AID and SID of CP and most AA, AID of starch, apparent total tract digestibility (ATTD) of GE and starch, and DE value of test ingredients. Steam-pelleting or extruding barley increased (P < 0.05) the ATTD of GE and DE value by 3% but not AID or SID of CP. Steam-pelleting faba bean increased (P < 0.05) the AID of starch, and the AID and SID of CP, Ile, Leu, Met, and Val by 3 to 12%. Extruding faba bean increased (P < 0.05) the AID of starch, and the AID and SID of Ile, Leu, Met, Phe, Thr, and Val by 3 to 10%. Steam-pelleting or extrusion increased (P < 0.05) the predicted NE value of barley and faba bean. In conclusion, heat processing increased the predicted NE value and amino acid digestibility of faba bean but only the DE and predicted NE value of barley.
Ruiz et al. (Tue,) studied this question.