| Abstract: | Cotyledons from 11 varieties of rapeseed and canola seed were extracted with hexane and analysed for tannins, α-amylase inhibition value, starch and available carbohydrate by conventional methods. The sinapine content (total sinapic acid esters plus free sinapic acid) was determined by a spectrophotometric method. Samples of soya bean cotyledons, high-tannin sorghum grain and commercial rapeseed and canola meals were also analysed for comparison. Sinapine in rapeseed and canola cotyledons was measured at mean levels of 2.67 and 2.85% respectively. Tannins were detected in these cotyledons but only at low levels. The α-amylase inhibition values were also low or negative. Starch was detected in negligible amounts, and available carbohydrate at 13–14%. The predicted metabolisable energy (ME) value of commercial rapeseed or canola meal for poultry was found to be numerically close to the determined value when the available carbohydrate value was reduced to 35% of the observed value. |
