Chemical composition and standardised ileal digestibilities of crude protein and amino acids in grain legumes for growing pigs

The study was conducted to determine chemical composition and standardised ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in currently available grain legume cultivars for growing pigs. Three consecutive experiments were conducted with six barrows each, fitted with simple ileal T-cannulas. In total, 18 assay diets including six different cultivars of faba beans (Vicia faba) and peas (Pisum sativum), respectively, five different cultivars of lupins (Lupinus luteus, Lupinus angustifolius) and one assay diet with a commercial soybean meal (SBM, 490 g kg− 1 CP as-fed) were fed according to a row-column-design. The assay feed ingredients were added to a corn starch casein-based basal diet at the expense of corn starch. Each diet was formulated to supply approximately 50% of CP and AA from the assay feed ingredient and casein, respectively. Furthermore, the basal ileal endogenous losses and SID of CP and AA in casein were estimated by regression analysis from apparent ileal digestible and total dietary contents of CP and AA. The SID of CP and AA in the grain legumes were determined in difference to SID of CP and AA originating from casein, after correcting the apparent ileal digestibilities (AID) of CP and AA in the assay diets for basal ileal endogenous CP and AA losses. The average SID of CP in faba bean cultivars (76%) and pea cultivars (79%) were lower compared to lupin cultivars (87%) and SBM (87%) (P < 0.05). The SID of all AA in faba bean cultivars were lower compared to lupin cultivars and SBM (P < 0.05). Digestibility values measured in the present study provide further information to accurately formulate diets for pigs based on standardised ileal digestible contents of CP and AA in currently available grain legumes for growing pigs.