Leafy spurge, Canada thistle and spotted knapweed – those aren’t exactly the forages you’d expect cattle to eat.

But over the past decade, a growing number of researchers and ranchers are beginning to believe that cattle can be trained to eat certain weeds. Among them is Valier, MT, rancher Tom Christiaens, who trained 15 heifers and a bull to eat Canada thistle last summer.

Christiaens and two fellow ranchers – Darryl Habets and Maurice Tacke – were part of a pilot program training cattle to eat weeds. It was funded through the Montana Farmers Union and based on similar programs successfully held in that and other states.

The five-day training process was “very simple,” says Christiaens. Soon afterward, his heifers were eating thistle tops along an irrigation ditch where weeds tend to be a problem.

Having the cattle trample and break plants in the thistle patch also seemed beneficial. He hopes that the trained cattle will pass the preference for weeds on to offspring this summer.

Although their forage value changes throughout the growing season, weeds are actually quite digestible, says Kathy Voth, who developed the concept.

They offer more leaf than stem and average 20-32% acid detergent fiber (ADF) and crude protein ranging from 11% to 22%, she adds.

Voth, who has worked with researchers and the Bureau of Land Management as an outreach and science liaison, now operates a consulting company called Livestock for Landscapes. The Loveland, CO, company has trained more than 1,000 cattle around the country to eat a variety of weeds – even thorny ones like diffuse knapweed and Dalmatian toadflax.

Her approach to using cattle to control weeds comes from studying decades of animal behavior studies, including work by Fred Provenza, Utah State University wildlife scientist. He studied how animals choose what to eat, which led to Voth’s focus on teaching cows to eat weeds.

Before putting cattle through the seven- to 10-day training that Voth suggests, know which weeds can be targeted and avoid toxic plants (see accompanying story,, below).

Then choose which animals to train. Voth suggests using younger animals, or those less likely to be culled. She likes working with heifers and cow-calf pairs, but says steers and bulls learn, too.

Train a small herd that will then train offspring and the rest of the herd, she adds. Voth typically trains 25-50 animals per project in pastures using recycled supplement tubs. She does not recommend troughs.

The key to Voth’s training is establishing a daily routine of feeding animals something nutritious but unfamiliar. This gives them positive experiences and makes them feel comfortable enough to try new foods. She feeds a new product twice a day for four days and introduces a chopped target weed on the fifth day. Cattle eat it because it’s just one more new thing in their routine of new things.

Here’s the kind of feeding schedule she suggests:

Day 1: morning – alfalfa pellets; afternoon – half alfalfa pellets, half rolled corn.

Day 2: morning – rolled corn; afternoon – rolled barley.

Day 3: morning – beet pulp pellets; afternoon – soybean flakes.

Day 4: morning – wheat bran; afternoon – hay cubes.

Day 5: chopped target weeds mixed with one of the above-mentioned feeds.

Day 6: target weeds with less feed mixed in.

Day 7: only weeds.

Then the cattle are returned to the larger herd and seek out weeds on their own.

After Christiaens’ cattle went through the training, they started eating musk thistle as well as Canada thistle, says the rancher’s brother, Chris Christiaens. He works with the Montana Farmers Union, helping to coordinate weed trainings.

Pastures that the brothers tested showed Canada thistle didn’t grow past 5” tall, which means it didn’t produce the seed heads that would cause it to spread.

Voth believes this manner of managing weeds is cheaper, more efficient and just as effective as herbicides. And she emphasizes that thistles don’t harm cattle.

Best of all, trained cows will continue to eat weeds year after year and add new weeds to their diet without additional training, Voth stresses. They’ll train others in the herd to eat weeds.

For more information, visit www.livestockforlandscapes.com.

Canada thistle, left, spotted knapweed, at right, and leafy spurge, below, can be consumed by livestock. Canada thistle photo: Norman E. Rees, USDA-ARS; spotted knapweed photo: USDA-APHIS PPQ Archive, Leafy spurge photo: Steve Dewey, Utah State University, all from bugwood.org. 

These Weeds Should Be Safe

Here’s a partial list of weeds that are edible and non-toxic for cattle to consume, says Kathy Voth:

  • Black mustard
  • Blackberry
  • Bull thistle
  • Canada golden rod
  • Canada thistle
  • Coyote bush
  • Diffuse knapweed
  • Distaff thistle
  • Field bindweed
  • Field scabious
  • Horehound
  • Italian thistle
  • Leafy spurge
  • Milk thistle
  • Multiflora rose
  • Musk thistle
  • Purple starthistle
  • Rabbit brush
  • Russian knapweed
  • Russian thistle
  • Sow thistle
  • Spotted knapweed
  • Wild rose
  • Willow
  • Wormwood sage
  • Yarrow
  • Yellow mustard
  • Yucca (leaves and blossoms)