Ileal amino acid digestibility and estimates of endogenous amino acid losses in pigs fed rapeseed meal, sunflower meal and soybean meal

Four commercial samples of rapeseed meal (RSM), four of sunflower meal (SFM ) and nine of soybean meal (SBM) were analysed and their ileal N and amino acid (AA) digestibilities in growing pigs were studied. Each batch was test ed on four castrated male pigs weighing between 40 and 100 kg and fitted wi th an end-to-end ileo-rectal anastomosis. True ileal digestibility (TD) of AA was calculated by correcting apparent ileal digestibility (AD) for basal endogenous AA losses, measured by means of a protein-free diet. For RSM an d SBM, total endogenous gut AA losses were estimated by a multiple regressi on model and real ileal digestibility (RD) of AA was calculated. In RSM, av erage TD of lysine, threonine and methionine were 70.7, 73.2 and 86.0%, res pectively. These values were 80.0, 81.8 and 91.9%, respectively in SFM and 90.5, 86.8 and 93.0%, respectively, in SBM. In SBM, TD decreased (P < 0.05) with increases in the ratio of dietary acid detergent fibre (ADF) to AA co ntents. Expressed as g kg(-1) dry matter (DM) intake, total endogenous gut N losses reached 4.7 to 6.4 for RSM and 1.9 to 3.5 for SBM. For SBM, they i ncreased (P < 0.001) with dietary ADF concentration and RD of most AA decre ased (P < 0.05) with the increase in the ratio of dietary neutral detergent fibre (DF) to AA concentrations.