|Jung, Hans Joachim|
Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2005
Publication Date: 1/10/2006
Citation: Casler, M.D., Jung, H.G. 2006. Relationships of fibre, lignin, and phenolics to in vitro fibre digestibility in three perennial grasses. Animal Feed Science And Technology. 125:151-161. Interpretive Summary: Livestock performance can be improved by increasing the digestibility of feeds, one of the key elements of feed quality. Digestibility of feeds can be improved by breeding forage crops with modified cell-wall structure ro increase the relative availability of energy in the cell wall to rumen microbes and livestock. We investigated the possibilities of breeding smooth bromegrass, orchardgrass, and reed canarygrass for reduced amounts of lignin or ferulates as a mechanism to improve digestibility. We found that breeding for low lignin levels would work well for this purpose in smooth bromegrass and orchardgrass, but that low ferulate levels are closely correlated with low fiber levels and this generally results in reduced forage yield. For reed canarygrass, we found that we need to select plants directly for improved digestibility. These results will aid us and other scientists in determining the most appropriate traits to use in breeding for increased digestibility of grasses.
Technical Abstract: Livestock performance can be improved by increasing the digestibility of feeds, one of the key elements of feed quality. Digestibility of feeds can be improved by breeding forage crops with modified cell-wall structure, increasing the relative availability of energy in the cell wall to rumen microbes and livestock. The objectives of this research were to identify interrelationships among lignin and phenolic components of the fibre fraction of three perennial grasses and to determine their influence on in vitro fibre digestibility. Differences in etherfied and esterified ferulic acid and p-coumaric acid among clones of three perennial grasses were generally repeatable across harvests. The concentration of neutral detergent fibre (NDF) and lignin within the NDF fraction were the factors most limiting to 24-hr in vitro digestibility, with NDF being the most important. Lignin and etherified ferulic acid were the factors most limiting to 96-hr in vitro digestibility for all three species. It should be possible to select and breed for low concentrations of lignin to improve digestibility without decreasing NDF in smooth bromegrass (Bromus inermis Leyss) and cockfsoot (Dactylis glomerata L.). However, in reed canarygrass (Phalaris arundinacea L.), both lignin and etherified ferulic acid were positively correlated with NDF, indicating that selection for increased digestibility should be based directly on some measure of in vitro digestibility to avoid the fitness problems associated with reduced NDF.