Using Cattle to Rehabilitate Rangeland Vegetation and Improve Ecosystem Function (3 yr project)

Final Report for OW10-321

Project Type: Professional + Producer
Funds awarded in 2010: $49,936.00
Projected End Date: 12/31/2013
Region: Western
State: Colorado
Principal Investigator:
Kathy Voth
Livestock for Landscapes
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Project Information


This three year project was a demonstration to show how or if we can manage cattle to reduce weeds and improve ecosystem function on Western rangelands. Our theory was that by using cattle trained to eat weeds and focusing them on weedy sites we could reduce weeds, improve soils, and increase the potential for native and grass species to return.

PDF Version of This Report

The attached PDF includes photos.


"Plans get you into things, but you've got to work your way out." Will Rogers

This quote from Will Rogers is the best description of the course of this project. When I prepared the proposal, I thought that three years was enough time to gather the information I thought I needed. I didn’t factor in extreme fluctuations in precipitation from cool temperatures and record rainfall in one year to a stock pond-emptying drought in the next. I also could not have anticipated that my project pasture would become the site of herbicide trials, or that a new biking and hiking trail would be built through the pasture with a trailhead parking lot constructed on a portion of my first trial pastures. Having spent almost 15 years building electric fence for both goats and cattle, I never imagined that this project would test my skills and knowledge beyond their limits. I especially did not plan for the hikers and bikers and herbicide researchers who would turn off the electric fence and let the cattle out. When endangered leopard frogs were discovered in the primary water source for the cattle grazing in the pasture during the second season of the project, it was just one more challenge in a series.

"Everyone has a plan until they get punched in the face." Mike Tyson

As these unforeseen circumstances came up, my assistant and I worked with the ranchers and our Boulder County partners to adjust grazing timing and location, cattle numbers and fence lines. The kinds of changes we made were always designed to help us meet our goal of demonstrating how or if cattle could be intensively managed in a a landscape to reduce weeds and improve ecosystem function.

Lessons Learned

Though we weren’t always grateful for the learning opportunities presented to us, we did learn a lot. I list the key points here and discuss them in greater detail later.

1. Electric fencing in arid climates is a special challenge that is not easy to overcome.

2. Mob Grazing presents significant challenges beyond simply managing the animals. Some were logistical, some were political, some were a result of how grazing has been managed in this area both historically and currently, and some were a combination of all three.

3. Cattle will focus on weeds on their own, and changes in weed populations can and do occur.

4. Change is hard.

Project Background

In spite of continued efforts to control invasive species and the best efforts of herbicide companies to develop products for their management, weeds continue to spread nationwide at an average rate of 14% per year. In 2000, farmers and ranchers were already spending $5 billion to control pasture weeds, and an additional $1 billion was lost due to reduced grazing potential, reduced wildlife-related recreation, higher levels of soil erosion and reduced water quality (Pimental et al 2000). Researchers Rejmanek and Pitcairn noted in 2004 that when a weed is wide-spread “biological controls may be the only long-term effective way to suppress its abundance over the invaded area.”

Managing weeds on rangelands in the arid west is difficult because weedy species are spread over many acres, increasing the cost and difficulty of using herbicides, fire and mechanical controls. In addition, herbicides may be doing more damage than good to our forage base. The title of the sixteen year study by Rinella et al summarizes his findings succinctly: “Control effort exacerbates invasive-species.” The paper concludes that, “Aside from a transient increase in grass forage production, herbicide provided little benefit to the livestock producer or the ecosystem we studied. One of the primary objectives of spraying was to increase cattle forage by decreasing Euphorbia esula (leafy spurge) production, but paradoxically, two sources of evidence suggest that herbicide ultimately increased E. esula production.” They note that their previous research showed that grasses and forbs compete with E. esula, and as herbicide leads to long-term suppression of several native forbs, it followed that reduced native-forb abundances would lead to increased production of the target weed. Thus, spraying was actually increasing their problem. Research by Fuhlendorf et al (2009) supported Rinella’s conclusions that herbicide did little for the producer’s forage base or bottom line. While forbs were reduced by herbicide, grass cover varied more due to annual precipitation than herbicide treatments and “...livestock production was not altered either on an individual basis (gain/head) or on an area basis (gain/ha).”

Both research and experience have demonstrated that grazing can be used to reduce weed populations when timing and intensity of grazing is managed to put stress on target plants. As the graph indicates, a plant’s palatability and susceptibility to grazing changes over the growing season, with both decreasing after seed set (Launchbaugh 2006). Since palatability is based on the nutritional value, it is obvious that we will have best luck with grazing when the plant’s nutritional value is higher. Since seeds may also be spread in the manure of grazing animals, it also makes sense that we avoid grazing after seed set. Thus by paying attention to the growth stage of the target weed, we can pick a time before seed set to graze for maximum impact.(See Plant Palatability Graph)

Can Cows Eat Weeds?

In 2004, I began working on a process to turn weeds into forage for cattle. The inspiration came from work done by Dr. Fred Provenza and his colleagues at Utah State University that described how animals choose what to eat. They found that animals learn first from their mothers what to eat, and then from internal feedback from nutrients and toxins in foods (Provenza 2003). My theory was that animals did not eat weeds because their mothers had not eaten them, but that if they were nutritious, and if I could get them to take a bite of a weed, they would experience good feedback and would learn to eat the weed in pasture.

I tested this theory in a pilot project at Grant-Kohrs Ranch National Historic Site in Deer Lodge, Montana. I have since refined the process so that anyone can teach a cow to eat a weed in just eight hours over seven days. Because weeds are generally as good or better than alfalfa in nutritional value (Voth, Livestock for Landscapes website), cattle will eat weeds in pasture and remember them year after year. By teaching cows to eat weeds, producers have more forage available and they reduce costs for weed management. Cows teach their herd mates and calves to include weeds in their diets and they continue eating weeds year after year, even adding new weeds on their own. For more on the training process visit

In 2007 and 2008 I used this process to train Babe and Leo Hogan’s cows to eat late-season diffuse knapweed and Dalmatian toadflax. In 2009 we moved these trained cows and their calves to the Mayhoffer pasture with 30 cow-calf pairs belonging to Bill Hogan. We wanted to watch as the trained cows taught the untrained cows to eat weeds.

The weeds the cows ate exceeded our expectations. They ate very little grass and preferred to graze in the weedy area created by prairie dogs on the south end of Mayhoffer (Voth 2009). Based on what we saw, we theorized that by managing them more intensively we could reduce weeds and increase grasses and native forages. Thus we developed and submitted a proposal for a demonstration project to Western Sustainable Agriculture Research and Education (Western SARE) to further explore this possibility.

We selected the Mayhoffer pasture for this demonstration because it had a significant invasive species problem and it was also easy for participating ranchers to move cattle into and out of. Before Boulder County acquired this property as part of its open space program, it was continuously grazed. Ranchers remember it as having some of the best forage in the area. However county managers were concerned that the big bluestem populations were decreasing as a result of grazing, and under their management 38 of Bill Hogan’s cow-calf pairs graze it for two to three weeks annually. Weed invasions in the pasture are quite large and include a growing population of diffuse knapweed, Dalmatian toadflax, tumble mustard, curlycup gumweed, broom snakeweed, horehound, wormwood sagewort, a variety of thistles and more. Weed invasions and soil erosion are being enhanced by a 200 acre prairie dog colony on the southern slope of the 500 acre pasture and on the upland portion where prairie dogs were once reintroduced. (See Mayhoffer Map)

Because educated cattle were readily eating weeds in this pasture, we wondered if focusing them on portions of the pasture using Mob Grazing techniques might lead to improvements. As enthusiast and mob grazing expert Greg Judy explains, pastures are stocked at the equivalent of 1600 head per acre (the mob), and animals are moved when they have "eaten half and trampled half." The purpose of this level of impact is to increase soil organic matter and nutrient cycling and improve the water cycle by incorporating plant material into the soil surface and improving it with manure and urine. Practitioners, including University of Nebraska Extension Specialist Terry Gompert, say that mob-grazed pastures show an increase in soil-organic matter of 450% in just a few years, as well as increases of up to 200% in native and forage species production.

We expected numerous challenges in exploring mob grazing in this area. Given that arid regions in the west do not typically have the same amount of biomass available for grazing or trampling, it seemed unlikely that gains could be achieved at the scale described by Gompert. We wanted to see what kind of changes we could expect. Another issue was that as currently managed mob grazing systems require intensive management of animals, with some operators moving cattle twice a day or more. This was the opposite of traditional management in the area where producers run a series of smaller herds of cattle on scattered pastures, grazing them season-long. It was the hope of our Boulder County partner that this project might demonstrate how herds could be combined on larger pastures to increase stocking density without increasing labor. With that in mind, we hoped to develop examples of the kinds of stock densities that would work best in more arid regions and how they affect forage and livestock productivity.

The basics of the three year proposal funded by Western SARE included:

• Working with weed-eating trained cattle belonging to Babe and Leo Hogan and Bill Hogan on the Mayhoffer pasture managed by Boulder County Parks and Open Space.

• Sharing information and gathering input from ranchers and the City of Boulder open space managers so that whatever grazing management we developed would work for them and others as well.

• Doing rangeland health assessments, repeat photo monitoring and other data gathering to determine if our management is having the results we hope for.


Fuhlendorf, S.D., D.M. Engle, C.M. O’Meilia, J.R. Weir, D.C. Cummings. 2009. Does herbicide weed control increase livestock production on non-equilibrium rangeland? Agriculture, Ecosystems and Environment. Volume 132: Issues 1-2, July 2009.

Launchbaugh, K.L. 2006. Targeted Grazing: A Natural approach to Vegetation Management and Landscape Enhancement. An American Sheep Institute Publication. Available online at:

Pimentel David, Lori Lach, Rodolfo Zuniga, and Doug Morrison. 2000. “Environmental and Economic Costs of Non- indigenous Species in the U.S.” Bioscience 50, no. 1. p. 53-65.

Provenza, F.D., 2003. Foraging Behavior: Managing to Survive in a World of Change. Department of Forest Range and Wildlife Resources. Utah State University.

Rejmnek, M., and M. J. Pitcairn, in Vietch, C.R. and Clout, M.N. (eds). Turning the tide: the eradication of invasive species, 2004. IUCN SSC Invasive Species Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.

Rinella, M.J., B.D. Maxwell, P.K. Fay, T. Weaver and R.L. Sheley. 2009. Control effort exacerbates invasive-species problem. Ecological Applications. 19(1), 2009, pp. 155-162.

Voth, K. 2009, GLCI 2009 Final Report:
Voth, K. Livestock for Landscapes web site:

Project Participants

Our primary partners in this project were Boulder County Parks and Open Space, Rob Alexander and Meaghan Huffman and the ranchers who supplied the cattle, Albert (Babe) and Leo Hogan and Bill Hogan. Brothers Babe and Leo owned the first cattle to be trained in Boulder County and their cousin Bill was the Mayhoffer pasture lessee. We met with our primary partners to plan for the upcoming season, make adjustments along the way, and then to talk about what went right at the end of the season, and what we would like to do differently.

The City of Boulder also owns extensive open space, some of which is managed for grazing and is adjacent to grazing lands managed by Boulder County Parks and Open Space. Because of this close relationship, I asked Andy Pelster of Boulder Open Space and Mountain Parks to act in an advisory capacity to the project. We share information and invited him to meet with us on site, and his thoughts about the politics, science and art of grazing management informed some of the lessons learned.

Initially we also had four ranchers participating in an advisory capacity: Al Green, Dick Miller, John Hall and Jim Roberts. None of them participated in the Rangeland Health Assessment training, nor in the end of the first year review, and since they didn’t return phone calls we understood that they were no longer interested in participating.

Project Objectives:

Here are the objectives as described in the original proposal. I will describe methods and what happened during the project in the subsection below.

1. Train City and County staff and participating ranchers in the use of rangeland health assessments to create a team of monitors. Spring 2010

2. Set up demonstration site pastures and manage cattle within them.

3. Conduct six rangeland health assessments for each of the demonstration areas over the course of three years. As it turned out, the pasture was in one soil type, so that doing rangeland health assessments over the entire area would not have given different results.

4. Develop draft criteria for managing high density grazing including number/pounds of animals per acre, how long animals should be in one pasture based on changes in forage. This criteria will be developed using input from participating ranchers, successful practitioners, available literature and adaptive management during the project. Criteria will begin development in the fall of 2010 and will be completed by the end of the project in 2012.

5. Create outreach and education materials to share with producers, City and County staff, media, County commissioners, open space advisory boards, NRCS and extension staff and others. These will include results in report form, flyer invitations and handouts for field days, and a video on DVD documenting the project. Results will
also be available on the Boulder County Parks and Open Space and the Livestock for Landscapes web site. Outreach and education materials will begin development in spring of 2012 and will be completed by the end of the project in 2012. Results will also be shared at annual meetings of producers with County and City staff.


Click linked name(s) to expand/collapse or show everyone's info
  • Rob Alexander
  • Al Green
  • John Hall
  • Albert (Babe) and Leo Hogan
  • Bill Hogan
  • Dick Miller
  • Andy Pelster
  • Jim Roberts


Materials and methods:


Before we could begin the grazing project, Boulder County determined it was necessary to spray 100 acres of the 500 acre Mayhoffer pasture to reduce diffuse knapweed. Every year they get complaints from the neighbors to the east of Mayhoffer because of knapweed skeletons that pile up on their fences, and this was an attempt to reduce their problems. To prevent this from impacting the project, our County partner, Rob Alexander, had us fence that area off so that cattle would not graze there. The fenced area is shown on the 2010 map.

For year one, we began fairly modestly, using only 80 cow-calf pairs plus bulls. This was an opportunity to test “mob grazing” and to see what kind of impact we would have on the weeds. Because we hoped to compare standard grazing with more concentrated grazing, we first brought the cattle into the 500-acre Mayhoffer pasture on June 10, allowing them to lightly graze the entire pasture as they would under normal management. Beginning on June 22, we confined the herd to small test pastures, focusing on areas heavy in “weed” species including diffuse knapweed, dalmatian toadflax, horehound, gumweed, musk and canada thistle, broom snakeweed, field bindweed and more. You can see the pastures and grazing course on the 2010 map.

The herd expanded to 100 animals on July 2. When someone opened a gate on the north boundary of the pasture, our herd joined with a smaller group grazing to the north. Since they all belonged to the same rancher, and it would have been very difficult to separate them, we simply included them in the project.

Our goal was to graze to the degree that each weed had been bitten at least once. By July 9, the cattle had worked on four separate pastures. During that time they had escaped from the electric fence twice, once when someone let them out and again when a thunderstorm took the fence down temporarily. They escaped again on July 9 when someone turned off the charger to the fence. Since the project was slated to end three days later, instead of herding them back to their pastures we released them from mob grazing and they were pulled from the pasture on July 12, 2010.

2010 Results

We toured the pasture several times with Rob Alexander and Meaghan Huffman, our Boulder County partners. Rob was very pleased with the level of impact on the pastures, noting where hoof action and manure had improved them for native forbs and grasses. Before and after pictures of some of the pastures are included after the 2010 map.

We also learned that given the amount of forage we had, 100 cow-calf pairs with bulls require about two acres per day. During our meetings with ranchers and with our Boulder County partners, we agreed that increasing the herd size to between 200 and 300 animals would allow us to cover more of the area that Boulder County hoped to have treated by cattle.

The cattle continued to expand the kinds of plants they grazed in pasture. This year they added curly cup gumweed, yucca and common mullein.


This was a difficult year for the project. An extremely dry winter was followed by a cold, wet spring. This entire area sees about 10 to 12 inches of precipitation annually, but this year five inches of that fell as rain during the month of May. The combination of a lack of winter moisture followed by rain and temperatures in the 40s and 50s for several weeks in the spring slowed vegetation growth so that we were two to four weeks behind normal.

Water was another serious problem. The southern ponds that we typically rely on to water livestock were empty at the end of April, and only partially filled after the May rains. Cattle can also usually water at the irrigation ditch at the northern boundary of the pasture. But this year, because of all the rain in May, irrigators were not calling for their water, so the community ditch was not turned on until the end of the second week in June.

The stock ponds we normally use in the middle of the pasture were not in working order. Piping had been broken or removed and left unrepaired, so the lower, larger tank could not collect water, and the smaller tank received only a trickle from the spring feeding it. The small pond above these tanks was only partially filled due to the dry winter.

Boulder County staff were reluctant to allow cattle access to the spring and stock tanks for reasons beyond lack of maintenance. First, Boulder County wildlife staff discovered leopard frogs in the pond at the end of the 2010 grazing season. Leopard frogs are rare and being considered for listing under the Endangered Species Act. The Boulder County Agriculture staff was concerned about potential overlap between the grazing season and the frog breeding season. We later learned that our grazing season did not overlap with breeding season. A second reason staff was concerned about using the central stock ponds was that a new, regional hiking and biking trail had just been built through the pasture. The edges of the trail had been seeded and were lined with straw anti-erosion barriers. Staff was concerned that cattle would cause damage to the seedings and barriers and that there would be conflicts with trail users.

To prevent problems with the frog and the trail users, we built new electric fencing to keep the cows in the western half of the pasture. Our plan was to graze the cattle first in the southern portion of the pasture and then, when we no longer had water in the ponds there, we would move the herd to the north end of the pasture where they would be able to water from the community ditch when it was ready.

In 2010 we had all agreed that we should begin grazing earlier in the season so that we could hit the Dalmatian toadflax when it was higher in protein. So our Boulder County partners asked us to begin our grazing season on May 27, 2011 with 150 cow-calf pairs. The problem was that “early” was measured by date, instead of plant growth stage, and since plant growth was two to three weeks behind the normal, there was much less forage for the animals. In addition, the early growth stage of the big bluestem made it much more palatable to the cattle and they grazed it in 2011 though they had not done so in previous years. This raised concern for our Boulder County partners and resulted in cattle being removed from pasture by the end of June.

We again had issues with the electric fence. The new fence was taken down several times by blowing tumbleweeds that accumulated overnight. When water got low, no fence would hold the cattle, and they broke out and headed for the the leopard frog ponds.

2011 Results

While the human participants struggled with all of these things, our cow colleagues just continued to do the job they’d been hired for. They did an excellent job targeting the most weed infested areas of the pasture, whether or not the electric fence was in place. When I returned in August and again in September, I could not find a single Dalmatian toadflax plant that had not been grazed. They also did a good job on late season diffuse knapweed, though their success would have been better if the human partners had been able to agree on the timing of bringing them back to pasture.

One of the indications of the willingness of animals to focus on weeds was that they waited at the electric fence keeping them from the knapweed in the northern pasture. I mistook their attention for needing water from the ditch on the northern boundary of Mayhoffer. I let them in, but instead of heading for water they ran to the knapweed patch and grazed it down.

Because research shows that grazing knapweed more than once in a season can reduce populations even more, ranchers and the county had agreed to putting a small group of cattle back in the northern pasture at the end of the summer. Unfortunately, I was not able to get permission from the county when the plants were ready for re-grazing. By the time I was allowed to put the cattle in, the plant had gone to seed and was no longer palatable. Though this didn’t achieve the hoped-for result, it did add an important bit of information. Graziers have often wondered if animals will cause weeds to spread by eating their seeds. Research indicates that animals would not eat plants gone to seed because of their very low nutritional value. That is exactly what we saw in this case. Animals avoided the weed in seed and ate everything else in pasture instead.

One of the best results to come out of this summer was evidence that grass is returning to replace weed species in the southern portion of the pasture. Participating ranchers are excited by the increase of sideoats grama in the pasture, and it is clear that there is more grass overall throughout the pasture. This year cattle also added broom snakeweed, rabbit brush and wild rose to their diets.


"It was a bad drought. It was the worst in the living memory of many farmers." Robert Geigengack, University of PA, Earth and Environmental Science Department

When I went to check the Mayhoffer pasture in the spring of 2012, I didn’t come home with good news. Crunchy was the best way to describe the pasture. In fact 2012 was drier than any of the dustbowl years, and the only year drier in Colorado history was 1895. In the Mayhoffer pasture, the only water for that year would be on the north end, provided by the community ditch.

Based on the conditions, we reduced our herd size to 38 of Bill Hogan’s cow-calf pairs and prepared for a very short grazing season on the north end of the pasture where the herd could drink from the irrigation ditch. The red lines on the map show our fence placement.

Bill moved the cattle to the pasture on June 7. When we arrived the morning of June 8, the cattle were out and grazing in the Leopard Frog/stock tank area. Bill came to put them in again for us. We made sure the fence was working correctly and also herded the cattle down to the irrigation ditch to make sure they knew where water was. We also placed a supplement tub on the upland portion of the pasture to further encourage them to stay put.

The cattle were out again on June 10, and then again on June 11, and each time we had to call Bill to help us put them back. In theory these were animals that we had worked with for four years, and in the past, even when they escaped we were able to herd them on foot back to their pastures. But these cattle seemed almost wild and had very little respect for the fence. We could not herd them back to the fenced pasture and had to call on Bill to come and herd them back with his 4-wheeler every time. In addition, though we saw some evidence that the target weeds were being grazed, it did not match what we were accustomed to seeing in previous years.

I called Bill Hogan to see if they were cattle that we had previously used, and he told me he had no idea what he had put in the pasture. His response matched our observations that most if not all of these animals were not trained to the fence, or to to eating our target weeds.

We were now faced with a decision about what to do for the remaining 10 days of grazing that Boulder County was allowing for grazing in Mayhoffer. We considered the importance of maintaining the health and safety of the animals, our inability to keep them fenced in the trial pasture, and that Bill Hogan had plenty of other work on his hands due to the drought. It seemed best for all concerned if we stopped trying to keep them in the trial pasture and give them the run of the entire area.

I went back later in the summer to check on pasture health. It seemed that the drought had set our progress back on diffuse knapweed and that though every Dalmatian toadflax plant in the pasture had been grazed, its population had expanded.

Research results and discussion:

Results were incorporated with the Methods section because yearly changes in the project were based on what had happened the previous year.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

1. Annual meetings with our participating ranchers and county staff to discuss lessons learned and develop plans for subsequent years.

2. What’s Edible publication on Livestock for Landscapes website that shares information on weeds cows can eat.

3. 2010 report outlining work and accomplishments for that year.

4. Final report. Reports are shared with all our partners and with Boulder County Commissioners and the Parks and Open Space Board. They will also be available on the Livestock for Landscapes Website.

5. Upcoming - Video on the project will be put up on Youtube at the Livestock for Landscapes channel:

6. As co-editor of the online grazing magazine “On Pasture” I will be excerpting portions of the reports and publishing them as articles in the magazine. Information about the video and list of weeds cows can eat is also being shared from this publication which has had over 21,000 views in the one month it has been online. (

Education and Outreach Outcomes

Recommendations for education and outreach:

Areas needing additional study

Drought had a huge impact on this project and its outcomes. The change in precipitation over the course of the project led to unanticipated problems with fencing, with providing cattle with water, and with being able to accomplish grazing goals on the ground. In the end, we had to so drastically reduce numbers that what remained could never have been considered a “mob.”

That said, here are recommendations that might help those considering trying more intensive grazing management:

1. Train your cattle to eat weeds. Educated cows were able to use all vegetation in the pasture as forage, and in years with normal moisture, this reduced how much grass they ate. The combination of increasing stress on target weeds, and reducing stress on species preferred by managers initially showed increases in grass species after the first year. Unfortunately drought stressed the grasses, reducing the overall impact of the grazing cattle.

2. Do everything you can to make your fencing successful. Train your cattle to electric fencing before putting them in the fenced area. Use these trained cattle every year, and if you don’t, be sure to train the ones you will use. When moving cattle into a new pasture, show them their water and don’t leave them at the gate where you turn them in. Thirsty animals are more prone to breaking through an electric fence, and so are bulls who are unfamiliar with each other. Last, consider putting ground rods along the length of the fence to enhance the fence’s overall charge.

3. Make a worst case scenario plan and go over it with partners or family members you will be working with. Make sure they are on board with the entire project, or make adjustments for concerns they have. Be clear about responsibilities and agreements about how you will handle difficulties such as drought before they happen. This will help you make a grazing plan that everyone can live with and is willing to work on through the hard times.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.