AMINO-ACID DIGESTIBILITY IN SOYBEAN-MEAL, EXTRUDED SOYBEAN AND FULL-FAT CANOLA FOR EARLY-WEANED PIGS

Studies were carried out with 12 early-weaned pigs (Lacombe X Yorkshire) to determine the amino acid digestibility values in soybean meal, extruded soybean and full-fat canola. The pigs were weaned at 21 days of age and fitted with a simple T-cannula at the distal ileum at 27 and 28 days of age. The pigs were fed on three maize starch-based diets formulated to contain 160 g crude protein kg(-1) from soybean meal, soybean meal plus extruded soybean and soybean meal plus full-fat canola, respectively, according to a two-period changeover design for three treatments. The pigs were fed three times daily, equal amounts at 08:00, 14:00 and 20:00 h, at a rate of 5% (wt./wt.) of the average body weight which was determined at the initiation of the first (8.9 kg) and the second (11.8 kg) experimental periods. Each experimental period comprised 9 days. Faeces were collected from 08:00 h on Day 6 to 08:00 h on Day 8. Ileal digesta were collected for a total of 24 h, at 6 h intervals, from 08:00 to 14:00 h on Day 8, from 20:00 h on Day 8 to 02:00 h on Day 9, from 08:00 to 14:00 h on Day 9 and from 20:00 on Day 9 to 02:00 h on Day 10. Chromic oxide was used as a digestibility marker. The apparent ileal digestibility values of extruded soybean and full-fat canola were determined by the difference method. The apparent ileal digestibility values of crude protein and most of the amino acids were higher (P<0.05) in soybean meal than in extruded soybean or full-fat canola. The difference in crude protein digestibility between soybean meal and extruded soybean was 11.2 percentage units; of the indispensable amino acids, the differences in digestibility values ranged from 8.9 (histidine) to 20.8 (leucine) percentage units. The difference in crude protein digestibility between soybean meal and full-fat canola was 11.4 percentage units; of the indispensable amino acids, the differences in digestibility values ranged from 7.8 (threonine) to 15.8 (histidine) percentage units. There were no differences (P>0.05) in the apparent ileal digestibility values of crude protein and the indispensable amino acids between extruded soybean and full-fat canola.