Producing High-Quality alfalfa is all about maximizing its digestibility levels for the animals that eat it. The main challenge to increasing digestibility is lignin. So when researchers, after years of study, identified the genes that influence lignin levels in alfalfa, it was a significant step in improving feed efficiency from this major forage. This year, after field trials and limited feeding tests, they are confident they've developed a more digestible alfalfa.

More milk, less manure

Because alfalfa is the fourth most widely grown crop in the United States, varieties with lower lignin levels could enhance animal production, improve profitability, and reduce the environmental impact of livestock operations. According to estimates by the U.S. Dairy Forage Research Center (USDFRC) in Madison, WI, just a 10% increase in alfalfa fiber digestibility would lead to a $350-million increase in U.S. milk and beef production each year and a 2.8-million-ton annual decrease in manure solids.

Seven years ago, a consortium of forage heavyweights, including researchers from the Noble Foundation, USDFRC, and Forage Genetics (a subsidiary of Land O'Lakes), began identifying the genetic pathway to making lignin in alfalfa plants, examining each step along the pathway and the genes involved, explains Mark McCaslin, president of Forage Genetics. “One by one, researchers at the Nobel Foundation knocked out a gene at each step to find candidates that led to decreased lignin, with no negative impact on agronomic traits,” he says.

While Noble researchers worked in the laboratory, Forage Genetics and USDFRC staff focused on field trials with two of the new reduced-lignin trangenic lines. “We consistently saw reduced lignin and increased in vitro fiber digestibility in the transgenic lines, so the next step was to feed it to animals,” McCaslin says.

Those feeding trials got under way this past year with lambs at the USDFRC facility in Madison and with dairy cattle at the Land O'Lakes Purina Feed LongView Animal Nutrition Center in Missouri. “The preliminary data look tremendously exciting,” McCaslin says. “The results so far are confirming our theories.”

Long-lasting quality

“What we've found is that the quality of these reduced-lignin lines lasts longer in the field, which could give producers a much larger harvest window,” he continues. “The animal tests confirm that, by decreasing the lignin, you increase fiber digestibility. And with higher fiber digestibility, the animal eats more. Increased feed intake and decreased manure solids are major potential production benefits for livestock producers.”

Future feeding trials with the low-lignin varieties will examine every aspect of the animal — from all the feed going in, to every bit of milk and waste coming out. But much of the agronomic testing of trait-specific alfalfa has already taken place.

“We tested these varieties in many locations and found them to be stable, with no major performance drawbacks,” McCaslin says. “We're planning for regulatory trials and could have a product on the market as early as 2013.”