The digestibility and content of amino acids in toasted and non-toasted canola meals

Abstract

A study was conducted to determine the level and digestibilities of amino acids and the level of glucosinolates in toasted and non-toasted canola meal samples produced in commercial crushing plants in western Canada. A total of 26 non-toasted and 31 toasted canola meals samples were analyzed for apparent ileal amino acid digestibilities using broiler chickens between 21 and 28 d of age. Commercially toasted canola meal contained 5.6 g 16 g-1 N (range 5.3–5.9) of Lys with a digestibility ranging from 65.5 to 85.7% (mean = 78.0%). Non-toasted canola meal contained 6.0 g 16 g-1 N (range 5.7–6.3) Lys with digestibility values ranging from 87 to 92% (mean = 89.7%). Toasted canola meal had an average total digestible amino acid content (not including Tyr and Trp) of 69.6 g 16 g-1 N (range 56.6–75.6) while non-toasted canola meal had 77.6 g 16 g-1 N (range 73.1–82.0). The levels of aliphatic glucosinolates in the toasted (6.16 μmol g-1 meal, range 1.2–12.5) and non-toasted meals (10.5 μmol g-1 meal, range 7.8–15.1) were low and likely of nonutritional consequence. In conclusion, non-toasted canola meal contains higher levels of digestible amino acids than conventional toasted canola meal and therefore consideration should be given to modifying commercial systems to produce a non-toasted meal. Key words: Canola meal, toasting, amino acid, digestibility, glucosinolates