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components of S. al& seed. In cornparison to full fat soybean, d a type S. alba contains more
oü (26.4 vs 20.2%) but less protein (37.5 vs 41.4%)(Kiede, 1998).
As early as 60 years ago, the outer seed mat of mustard seeds was first reported to be rich in
mucilaginous material (Bailey and Noms, 1932) which was later attribut4 by Weber et al. (1974)
to the consistency of prepared mustard products. Cui et al. (1994) reported that crude mucilage of
yeliow mustard seed made up 5 % of the seed weight with water-soluble and water-insoluble fiactions
accounting for 55.6 % and 3 8.8 %, respectively. In the study by Kienzle (1998), the canola type S.
a h was found to contain 1.7 % water-soluble fiber (Le., mucilage) which was higher than that
present in soybean or B. nupus canola. Although mustard mucilage is widely used by the food
industry (Le., salad dressings, food pastes) its viscous characteristic would appear to be a ümiting
factor in monogastric animal feeding. Viscous polysaccharides including mucilage, gums, pectins and
some hemicelluloses (Le., arabinoxylan, p-glucan) have been reported to affect nutrient absorption
by interfering with bulk movement, preventing mixing of nutrients with digestive enzymes and
eliminating transport of nutrients to intestinal rnucosa (Kritchevsky, 1988; Johnson and Gee, 198 1;
Campbell and Bedford, 1992).
1.2.3. Nutritive Value
Available energy content is ofgreat importance in assessing the nutritive value of feedstuffs. True
metabolizable energy (T'ME) or TME corrected to zero nitrogen balance (TMEn) is gaining wide
acceptance in feed evaluation since both TME and TMEn values are obtained by making corrections
for metabolic and endogenous losses. The metabolizable energy content of feedmffs is offen
influenad by factors associated with fat or carbohydrate digestibility and, as reported for
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