|Jung, Hans Joachim|
|Samac, Deborah - Debby|
Submitted to: CD ROM
Publication Type: Proceedings
Publication Acceptance Date: 7/11/2001
Publication Date: 7/20/2001
Citation: JUNG, H.G., LINN, J.G., LAMB, J.F., SAMAC, D.A., SOMERS, D.A. IMPROVING ALFALFA FIBER DIGESTIBILITY. FOUR-STATE APPLIED NUTRITION AND MANAGEMENT CONFERENCE. 2001. CD-ROM. UNIVERSITY OF ILLINOIS. Interpretive Summary: Feed is the single largest non-fixed cost of milk production, so providing high quality feed and balancing nutrients in dairy cow diets is critical to profitability. The Four-State Applied Nutrition and Management Conference provided dairy producers, nutritional consultants, feed industry personnel, and other dairy professionals updates on numerous topics related to feed quality, diet formulation and requirements, and cow management at a meetin in La Crosse, WI. A CD was compiled for future use at extension meetings that included all presentation materials and recordings of the speakers' comments. One presentation provided a description of efforts by USDA-ARS and University of Minnesota scientists to increase the digestibility of alfalfa stems. This research has been undertaken because stems account for most of the yield increases associated with more mature alfalfa, but stems are poorly digested. It was reported that breeding for reduced stem fiber concentration and increased digestibility appears to be possible, that the first attempt at increasing the pectin content of alfalfa using biotechnology was unsuccessful, and that very fine grinding of alfalfa might substantially increase energy availability from stems. Additional research and development by USDA-ARS and other scientists will be needed to convert these preliminary findings into applied practices that can be utilized in commercial dairy production.
Technical Abstract: It is apparent that rising fiber (cell wall) concentration and declining digestibility of stems as alfalfa matures accounts for the limited digestible energy available from alfalfa. The changes in fiber concentration and digestibility can be explained by the proliferation of lignified xylem tissue in the stem, thereby identifying this tissue as an appropriate target for modification to improve the quality of alfalfa. Genetic variation exists in alfalfa for cell wall concentration, composition, and digestibility. Breeding for improved alfalfa fiber digestibility should be successful if heritability of the trait is adequate. Biotechnology is another tool available for genetic modification and offers promise for altering cell walls of alfalfa, but success awaits a better understanding of how to manipulate important quality traits to achieve the desired outcomes. Fine grinding may offer an opportunity to increase the digestibility of alfalfa stems by providing rumen microbes access to potentially digestible cell wall carbohydrates that currently are lost in the feces.