Author
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Buxton, Dwayne |
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Redfearn, Daren |
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Submitted to: Journal of Nutrition
Publication Type: Review Article Publication Acceptance Date: 4/22/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Energy availability from forages is limited by fiber concentration because fiber is slowly and incompletely digested, whereas cell solubles are almost completely digested. Thus, the proportion of fiber to cell solubles is a major determinant of energy availability in forages. Grasses normally have more fiber than legumes, especially in leaves. Grass fiber is more digestible than that of grasses, but that of legumes digests at a faster rate. Ruminants digest 40 to 50% of legume fiber and 60 to 70% of grass fiber. Some fiber cannot be digested no matter how long it remains in the rumen. Lignin is thought to interfere with microbial degradation of fiber polysaccharides by acting as a physical barrier and by being cross-linked to polysaccharides by ferulate bridges. Physical and structural barriers may limit fiber digestibility beyond the effects of lignin. Because the middle lamella and primary wall of thick-walled cells are so highly lignified, many cells can only be digested from the interior of the cell. For many cells, access to cell interiors is limited because of large particle sizes. Forage digestibility could be improved by reducing the amount of lignified cells or by developing improved cultivars so that lignified cells are more digestible. |
