Author
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Jung, Hans Joachim |
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Buxton, Dwayne |
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Submitted to: Meeting Abstract
Publication Type: Proceedings Publication Acceptance Date: 9/16/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The three primary roles of forages in dairy rations are to provide fiber for maintenance of healthy rumen function, energy for milk production, and protein in the case of legumes. The first two forage functions are related because it is the plant cell wall which constitutes the fiber fraction and the cell wall is of limited digestibility, thereby influencing energy availability. As genetic potential for milk production of cows is improved, their energy requirements increase. Therefore, to meet both the ever increasing energy requirements of high producing dairy cows, and still provide them with the fiber they require for rumen health, demands that we find ways to improve cell-wall digestibility to allow forages to contribute more energy for milk production. The Cell Wall Group of the US Dairy Forage Research Center has focused on the composition and structure of cell walls as the determining factor for digestibility. In this paper we discuss efforts to identify the components of cell-wall lignification that both negatively impact digestibility and are amenable to genetic modification through either plant breeding or molecular biology. Our research indicates that lignin concentration is a good predictor of maturity but is not well correlated with cell-wall digestibility within maturity stage. Lignin composition, as measured by syringyl-to-guaiacyl ratio of monolignols, does not appear to impact digestibility of the cell wall. Lignin/polysaccharide cross-linking in grasses by ferulic acid appears to be a major determinant of cell-wall digestibility. Genetic variation has been found for all elements of cell-wall lignification indicating selection should be possible for improved digestibility. |
