Description:
Tryptophan availability in wheats (No. 1 Canada Western Red Spring milling wheat, Neepawa; No. 1 Utility wheats, Glenlea, Norquay and unlicensed Purple PFW606A), soybean meal (SBM) and rapeseed meal (RSM) processed under different conditions was calculated by balance trials with rats. Tryptophan availability values (95–96%) in the different wheat cultivars were similar. Tryptophan in the SBM and the RSM (untreated) was 94 and 90% available, respectively. Isolation of proteins from the meals seemed to have a slight beneficial effect (1–2%) on availability. Diffusion extraction and 2-h autoclaving had no effect on the availability of tryptophan in the RSM (untreated), but severe heating (4 and 6 h) reduced the availability by 20 and 52%, respectively.