Location: Dairy Forage ResearchTitle: Reduced Lignin Alfalfa - Update Author
Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/22/2010
Publication Date: 1/25/2010
Citation: Martin, N.P., Hatfield, R.D., Undersander, D.J. 2010. Reduced Lignin Alfalfa - Update. In: Proceedings of 2010 Symposium of the Midwest Forage Association, January 26-27, 2010, Wisconsin Dells, Wisconsin. Midwest Forage Association Presentations, Tuesday, 2. Interpretive Summary:
Technical Abstract: U.S. farmers harvested alfalfa (Medicago sativa) for hay or haylage from 24.5million acres in 2009. Midwestern states harvested 57 % of 2009 acreage for hay and haylage. However, acreage is stable to declining. Alfalfa provides an excellent source of fiber, protein, minerals and vitamins that partially or completely meet various classes of ruminant livestock nutrient needs. If alfalfa could be engineered to increase the extent of fiber digestion the amount of energy derived from cattle diets would increase or the potential amount of carbohydrate available for cellulosic ethanol fermentation could increase; each of which has potential to increase the demand for alfalfa. Higher value livestock feed, potential for a new cellulosic feedstock and potential to reduce the number of cuttings per season supports the need for alfalfa variety improvement. The Consortium for Alfalfa Improvement (CAI) is a partnership model of government, private non-profit and private profit entities needed to advance long-term, high risk science that potentially will develop large payoffs for ruminant livestock producers. The CAI has been committed to redesigning alfalfa for dairy cattle, reduction of cell wall lignin and reduction protein degradation during fermentation. Lignin is a component of plant cell walls (fiber portion) that is like a plastic coating cellulose fibers making them repel water. This property allows water transport within the plant without leakage and provides strength to plants. Lignin increases with advanced maturity in alfalfa. However, lignin is indigestible and reduces fiber digestibility in ruminants. Proof of concept reduced-lignin transgenic alfalfa hay fed in total mixed diets with corn silage measured increased fiber digestibility in both lactating dairy cows and rapidly growing lambs. Digestible dry matter of one transgenic increased 3.5 % fat corrected milk over the same plant population without the reduced-lignin gene by 2.86 lb/hd/day. Alfalfa stems from reduced lignin genotypes increased sugar yield which potentially could increase ethanol > 50% compared to standard alfalfa. Two reduced lignin transgenic alfalfa populations were compared to appropriate controls and grown in diverse environments. Harvests were taken beginning at late vegetative stage and continued at 5 day intervals for 5 total harvests. Forage samples were analyzed for crude protein, neutral detergent fiber, acid detergent lignin, and neutral detergent fiber digestibility (NDFD). Late harvested COMT and CCOMT lines had the same NDFD as their control populations harvested 8 to 12 days earlier. Producers using this trait may be able to delay harvest while maintaining forage quality, potentially eliminating one or more annual harvests while increasing yield by 20 to 30%.