Ileal digestibility of amino acids in co-extruded peas and full fat canola for growing pigs

An experiment was conducted to determine coefficients of ileal apparent digestibility (CIAD) and ileal true digestibility (CITD) of amino acids (AA) in co-extruded peas and full fat canola products differing in canola type (standard and heated) and days elapsed from mixing to extrusion (D-0 and D-10). Heated canola contained a blend of standard canola and 80 g/kg of heated canola as defined by Canadian Grain Commission (CGC) grading standards. Peas were mixed with either standard or bin heated canola seeds (50:50, w/w) and a part of each mixture was extruded immediately (D-0) and the other part later (D-10). Four diets were formulated to contain each of the four products (650 g/kg) as the sole source of AA. A fifth diet containing casein (50 g/kg) was used to estimate basal endogenous loss of nitrogen and AA. Chromic oxide (Cr2O3) and HCl insoluble ash (HCl-IA) were included in all diets as indigestible markers. Diets were fed to 5 growing barrows, average BW 66.3 ± 4.9 kg, and fitted with a simple T-cannula at the distal ileum according to 5 × 5 Latin square design. Experimental periods lasted 6 d and ileal digesta was collected in 12-h periods on D-5 and D-6. Digestibility values obtained with the two markers were pooled as they were established to be similar. There was an interaction (P<0.05) between canola type and days elapsed to extrusion in CIAD and CITD of crude protein (CP) such that extrusion after 10-d storage increased CIAD and CITD of CP of the diets containing heated canola only. An interaction (P<0.05) between canola type and days elapsed to extrusion in AA digestibility was observed in CIAD of aspartic acid and CITD of aspartic acid and glutamic acid. Extrusion after 10-d storage increased CIAD of aspartic acid and CITD of aspartic acid and glutamic acid of the diets containing heated canola only. Except for methionine and proline, extrusion of peas and canola mixture after 10-d storage increased (P<0.05) CIAD and CITD of AA regardless of canola type. The mean CIAD and CITD for indispensable AA ranged from 0.666 to 0.767 and from 0.725 to 0.832, respectively. In conclusion, canola type had no affect on AA digestibility of co-extruded peas and full fat canola products; however, extruding the mixture after 10-d storage increased AA digestibility regardless of the canola type indicating quality improvement over time.