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Purple Prairie Pasture Enhancer Being Studied

Old is new again.

A native forb species once common on the Prairies is being studied as a cure for tired pastures and as a livestock feed with beneficial and unusual attributes.

Purple prairie clover is a palatable legume that can be grazed at various stages of maturity. Sporting a purple, cone-shaped flower, the warm-season, tap-rooted, drought-resistant, nitrogen- fixing legume grows about knee-high.

The seeds are about the same size as alfalfa seed, and contained inside the cone-shaped seed head.

Although it does not produce large amounts of biomass like alfalfa, it fits into an important ecological niche in native prairie landscapes and adds resiliency to pastures on marginal lands typically used for grazing livestock.

Under proper grazing management, it tends to be an increaser, unlike its tame cousins, which eventually disappear and need to be reseeded.

“We had originally put it in the mixtures just to provide more biodiversity, but we found that the animals don’t have a problem as far as grazing it,” said Alan Iwaasa, a ruminant and grazing management specialist at AAFC’s Semiarid Prairie Agricultural Research Centre in Swift Current.

“It does fix nitrogen so it adds a benefit for sustainability.”

The latest research is looking at the potential for reintroducing it to overgrazed pastures without the need to break up the existing stand.

A new tactic, called “deferred rotational grazing” has been particularly effective at boosting purple prairie clover populations already in pasture stands, said Iwaasa.

CATTLE DO THE SEEDING

It works on a three-year rotation. In the first year, the paddocks are grazed in the spring, then rested all summer. The pasture is grazed in summer in year two and then in the fall in year three “so when the animals get on there, the purple prairie clover has already gone to seed and it passes through the animals,” said Iwaasa.

“If it’s a very good year with moisture, we see a lot of the purple prairie clovers are actually sprouting up through the cow patties.”

For pastures that don’t have the plant, introducing it might be as simple as feeding winter hay out on the pasture with mature seed heads in it, or mixing the seed in with winter rations, as some have done with cicer milk vetch or sanfoin.

Passing through the digestive tract helps open up the protective seed coat, which improves germination.

In terms of forage quality, its digestibility averages 65 to 50 per cent and protein content averages 20 to 12 per cent from the vegetative to seed pod stage, respectively.

MID-SEASON BOOST

Since purple prairie clover is a warm-season forage legume, much of its growth occurs during July and August. Generally, this is the time when many cool-season grasses are in a mid-summer nutritional slump or entering a dormant stage due to drought.

This makes purple prairie clover an excellent addition to a pasture, as it can improve the nutritional profile and help extend the grazing season.

Researchers at AAFCLethbridge and AAFC-SPARC have found that purple prairie clover contains unique condensed tannins, which can not only improve protein utilization by cattle but also inhibit the growth of E. coli.

Normally, Iwasa said, ruminants avoid plants with condensed tannins, possibly due to their bitter taste. But for some reason, they are willing to eat purple prairie clover at all stages of its life cycle.

Condensed tannins are interesting because they create “bypass proteins,” he added.

These protein sources offer more nutritional bang for the buck. Instead of being broken down by rumen flora, they survive intact until they reach the small intestine where the animal is able to get the full benefit.

That improved nitrogen use efficiency not only makes purple prairie clover bloat-safe, it also reduces methane and nitrous oxide emissions, too.

Studies are underway on how to best utilize prairie purple clover in a grazing system for Western Canada. Work will continue until 2012.

AAFC researchers and Ducks Unlimited Canada have developed the plant as an “ecovar,” or environmentally friendly cultivar. It is produced under very limited selection pressure in order to preserve its beneficial wild traits and genetic diversity. Called “Lemar” it is available from Brett Young Seeds. daniel. [email protected]

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Ifit’saverygoodyearwithmoisture,wesee alotofthepurpleprairiecloversareactually sproutingupthroughthecowpatties.”

– ALAN I WASA

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