Sweeten it; they will come – Can cattle be taught to eat noxious weeds?

In a scientific program conducted by researchers at Utah State University, yearling heifers at Grant Kohrs Ranch National Historic site at Deer Lodge are being trained to eat noxious weeds as a portion of their diet.

Research project uses cattle for noxious weed control

Sheep and goats have been used for years to control noxious weeds in parts of the West, but can cattle be trained to do the same, without starving them?

By Pat Hansen for The Montana Standard

http://www.mtstandard.com/articles/2004/06/24/newsdeerlodge/hjjfjdhhjcecgi.txt

That’s the question researchers are studying in a field test at the Grant Kohrs Ranch National Historical Site at Deer Lodge.

Frederick Provenza at Utah State University has been researching the possibility for the past 20 years in a livestock behavior modification program. Now, the area field test has piqued the curiosity of ranchers in the Deer Lodge Valley.

Project coordinator Kathy Voth says successful demonstrations in other areas indicate that livestock behavior can be modified — as an economical alternative to chemicals to enhance biodiversity in rangelands, restore pastures dominated by invasive plants and improve wildlife habitat.

For the past eight years Voth has worked with Provenza and Ben Bobowski, chief resource manager at Grant Kohrs Ranch. She said the park service has an initiative program that provides money for research. Last year she, Provenza and Bobowski put together a proposal to conduct the project at Grant Kohrs.

The goal is to restore the cultural and natural landscape of the ranch by reducing the quantity and distribution of leafy spurge, Canada thistle and spotted knapweed. The objective is to teach cattle to mix their diet so that when they are rotated through pastures, they eat not only the preferred grasses and forbes, but the less desirable plants.

Because young cattle are more open to trying new foods, the ranch selected 18 yearling heifers to participate in the study. They chose females because mothers pass food selection knowledge to their young; therefore, the project will have a greater impact as the heifers have calves.

Key to the project is the understanding that animals choose their diets based on their experience with foods. Throughout the winter these cattle have been introduced to grains and hay flavored with molasses and fed in black tubs — to train the animals to associate "good food" with the black tubs. Research indicates that the more variety an animal eats, the less afraid it is to try new foods with a similar taste, Voth said.

The target weeds are being introduced one at a time. All plants contain some level of non-preferred chemicals. One of the secrets behind the ability of invasive species to out-compete native plants is their high levels of toxins. Animals protect themselves from these chemicals by avoiding or limiting their intake of these plants.

Two weeks ago, the heifers — which average 650 pounds — were introduced to Canada thistle, last week to leafy spurge, and this week to spotted knapweed. Each day 30 pounds of weeds are harvested by hand in the afternoon when the plants have the highest nutrition value. They are sprayed with half a gallon of Nutralix (a molasses/mineral formula) and mixed with seven pounds of corn, oats and barley. The mixture is put into 15 black tubs in the corral; in a nearby feeder they are fed 385 pounds of native grass hay, and an automatic system provides fresh water.

The weeds represent less than 10 percent of the heifers’ total diet. The cattle move back and forth between the buckets and the feeder mixing their food.

"We’re really pleased. It’s working much better than we thought," Voth said.

Toxins in the noxious weeds present concerns, which the project addresses.

Canada thistle has nitrate that can accumulate in the stomach. However, molasses and corn speeds the chemical process to ammonia, thus reducing the accumulation of nitrite and the potential for sickness or death.

Leafy spurge and knapweed have not been identified as health risks, though chemicals in them may reduce the quantity animals will eat. Leafy spurge has been known to cause blisters in the mouths of animals, but daily checks did not reveal any blisters.

Voth is uncertain how the chemicals in knapweed will affect the animals.

"They are not associated with poisoning," she says, "but they could cause the cattle to have a stomach ache. A lot of this is really new, but we will try different supplements that might increase consumption of these species and assist in digestion."

The animals are monitored closely for signs of distress. Staff members are also using low-stress livestock handling techniques.

Bobowski says the animals are weighed every other week .

"Ten days into the program they had an average daily weight gain of 3.1 pounds per day," he said.

Dr. Phil Murphy, a local veterinarian who serves the ranch and is assisting with the program, said, "These cattle are in good condition, and have a body score appropriate for replacement heifers that will be bred soon."

Next week Voth says the animals will be moved to small pastures, formed by electric fences, containing enough forage for one day. This will ensure that the animals have to mix foods rather than eating the best and leaving the rest. The cattle will be moved into a normal grazing system once they are eating the target species in the smaller pastures.

Daily progress of the project can be tracked on the Web site: http://livestockforlandscapes.com/stl-web/b2/

n Pat Hansen of Avon is a freelance writer and a frequent contributor to The Standard. She may be reached via e-mail at [email protected].