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Featuring a bloatless legume.

While they have many advantages, legumesespecially alfalfa-have one major drawback as a green forage:

They often cause animals to bloat.

Bloat is the buildup of gas in the cow's stomach caused by the rumen bacteria. Unlike humans, cows can't burp enough to relieve the gas. Instead, they swell up like big balloons and, in severe cases, suffer cardiac arrest or suffocation. So why not a bloatless legume? If ARS plant geneticist Paul Beuselinck is successful, increasing the use of a 1ongunappreciated legume with a picturesque name will help.

Birdsfoot trefoil contains a natural antibloating compound known as tannin.

Tannins help cows digest their food more slowly. In the rumen, these compounds bind to plant proteins, making them resistant to breakdown by rumen-dwelling bacteria. This slows down the rate of digestion. Further protein breakdown occurs when the nutrients reach the intestine.

"This legume has just the right amount of tannins-not too much and not too little," says Beuselinck.

Tannins are so desirable that another ARS scientist, Allan Zipf, a molecular biologist in Logan, Utah, is trying to genetically engineer them into alfalfa.

His method is to coat tiny tungsten pellets with the DNA from sainfoin, a plant that's known to contain tannins. The pellets are loaded into a 22-caliber cartridge and blasted into alfalfa cells with a special gun.

Only a small percentage of the DNA ever makes it into the plant material, but if a lucky shot becomes permanent, alfalfa will start producing just the right amount of tannin. [For more on sainfoin, see Agricultural Research, February 1991, p. 18.]

In other research, Beuselinck found that birdsfoot trefoil and tall rescue grass make good companions. They can be grown together, and together they produce a forage that's more nutritious for animals than just tall rescue alone.

Bacteria living on trefoil roots take nitrogen from the air and produce a nitrogen-containing protein that reduces the need for fertilizer for both the trefoil and the rescue.

"Trefoil looks like a fine-stemmed alfalfa with yellow flowers shaped like small sweetpeas. The plant tolerates poor soil conditions and abuse from grazing animals much better than alfalfa," says Beuselinck.

The plant has a taproot system, much like a carrot, only with branches. Birdsfoot trefoil has higher nutritional quality than alfalfa and doesn't decrease in quality as the plant matures the way alfalfa does.

Even with all its desirable qualities, birdsfoot trefoil doesn't enjoy immense popularity as a forage crop. That's because it's very susceptible to root disease. The answer to this problem, according to Beuselinck, may be linked to the plant's wild relatives from Morocco.

In 1989, Beuselinck collected wild birdsfoot trefoil in Morocco. Plants he found there have a unique rooting characteristic: the ability to develop rhizomes-underground runners-that allow the plant to spread to new areas. Then, even if the mother plant dies of disease, new stands of rhizomeproducing trefoil would survive.

Beuselinck believes it is possible to move the genes for rhizomes into higher yielding American varieties through either breeding or genetic engineering.-By Linda Cooke, ARS.

Paul R. Beuselinck is in the USDAARS Plant Genetics Research Unit, 207 Waters Hall, Universit)' of Missouri, Columbia, MO 65211. Phone (314) 882-6406.
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Title Annotation:includes information from a forage research symposium
Author:Cooke, Linda
Publication:Agricultural Research
Date:Mar 1, 1992
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