CARBOHYDRATES AND DIETARY FIBER COMPONENTS OF YELLOW-SEEDED AND BROWN-SEEDED CANOLA

Meal samples derived from a number of yellow- or partly yellow-seeded varieties/lines of canola were analyzed for carbohydrate and dietary fiber content and shown to contain 8-10% sucrose, 2-3% oligosaccharides, 20-22% nonstarch polysaccharides (NSP), and 5-8% lignin and polyphenols. The sucrose content was positively correlated (r = 0.66) with the percentage of yellow seeds in canola samples and was higher by 3-4 percentage points in fully yellow-seeded cultivars as opposed to brown-seeded varieties. Approximately 15 and 40% of the NSP fractions were found to be soluble in water and neutral detergent fiber (NDF) solution, respectively. Due to the high solubility of NSP in the NDF solution and because of a low content of lignin and polyphenols, the NDF values for yellow-seeded canola averaged only 19% as compared to 26% for brown-seeded canola. The total dietary fiber, however, was found to be 27% on average which is only slightly lower than that estimated for brown-seeded canola (30%). On average in comparison to brown-seeded canola, yellow-seeded canola was shown to contain more sucrose and much less lignin and polyphenols. Although the digestibility values were low, the digestibility of NSP from yellow-seeded canola meal was higher than that for brown-seeded canola meal (8.6 vs 3.4%) when measured with laying hens fed semipurified diets. Dry matter and amino acid digestibilities also tended to be higher for yellow-seeded canola meal.