Alfalfa with reduced lignin looks good in Idaho trials

As the debate about genetically modified crops continues to swirl around forage producers, agriculture researchers are refining gene modification techniques to improve forage quality. The most recent is reduced lignin, or RL, alfalfa.

According to Peter Reisen, director of plant breeding, Forage Genetics International, Nampa, Idaho, lignin is an indigestible component of plant cell walls. Lignin is essential for cell wall structure and provides rigidity in plants to keep them standing and cells from collapsing. As grasses and legumes mature, lignin increases making these forages progressively less digestible.

Key Points

• Continued genetic engineering research yields improved alfalfas.

• Reduced-lignin alfalfa promises improved feed quality.

• Alfalfa growers could increase yields and maintain quality with new alfalfa.

In 2003, Forage Genetics International joined with the U.S. Dairy Forage Research Center and the Samuel Roberts Noble Foundation to create the Consortium for Alfalfa Improvement. The organization is dedicated to “improving alfalfa characteristics that affect forage quality and efficiency of use by dairy cows.”

The group reports an alfalfa with lowered lignin content using a biotech process to greatly reduce expression of a specific individual gene. This “gene knockout” shuts off enzymes that produce lignin. The resultant alfalfa varieties show 10% to 20% improvement in fiber digestibility.

Under field conditions, these varieties produced 3.6 tons per acre in contrast to the 3.5 tons produced by control alfalfa varieties grown in the Nampa, Idaho, area. Trials have also shown that RL alfalfa harvested at 10% bloom is equal to or better than conventional alfalfa harvested seven days earlier at the early bud stage.

Digestibility plus

In tests on lactating dairy cows, Reisen’s data showed increased digestibility of RL alfalfa. “There was significant improvement in milk production with the lower lignin content,” he says, “There was no increase in dry-matter intake.” A side benefit of greater fiber digestibility is less manure produced from the same amount of alfalfa.

According to forage agronomist Dan Undersander, University of Wisconsin Extension, alfalfa producers should find increased production from RL alfalfa. At bud stage, alfalfa growth per day can be 200 pounds or more per acre. As conventional varieties mature past early bud stage, forage quality diminishes. With RL alfalfa, growers can delay harvest eight to 12 days while maintaining high-quality forage. By harvesting three vs. four cuttings within the same time period, alfalfa yield was 20% to 30% greater for the three-cut system.

Tews writes from Shoshone, Idaho.


COMPARISON TRIAL: The quality of this field of reduced-lignin alfalfa was similar to earlier harvested conventional varieties with nearly a 30% increase in production.

This article published in the August, 2010 edition of WESTERN FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2010.