Cows Not Chemicals: Training Cattle to Eat Invasive Weeds

by Shahla Farzan / The Mindful Californian

A heifer in Alberta, Canada eating Canada Thistle, Cirsium arvense (credit: Fito Zamudio).

A haiku
The War on Weeds ends
When cows begin to eat them.
Foe becomes forage
– The Tao of Cow

In 2004, Kathy Voth had a revolutionary idea: instead of using herbicides to control invasive plants on grazing lands, why not teach livestock to eat them instead? Using a surprisingly simple training routine, a rancher can train cattle to eat even the prickliest weed in as little as ten hours. The method relies on the herd mentality: teach a small group of young animals that unfamiliar foods can be tasty and their herdmates will follow. And like elephants, cows never forget, so ranchers need only train a small subset of their herd once. Sound too good to be true? Read on.

How did you initially develop the idea that cows might make good weed managers?
It actually started with goats. I was a public information officer in Colorado in 1994 when a fire killed 14 firefighters. This got me thinking about the dangerous positions we put ourselves in when we fight fires. At around the same time, I got a pet goat. Most people know that goats eat just about everything, so I started wondering if we could use goats to reduce fire risk. A friend of mine and I started a research project with a small group of goats and did a lot of research on the best ways to use goats for fire risk reduction.

In the process, I did some work to see which weeds goats would eat. I started going around to ranchers and saying, “You know, there’s research that says that if you have 5 goats for every one cow, you’ll improve your pasture.” They just looked at me like I was insane. Most ranchers don’t want to have goats in their operation because they require a completely different kind of fencing and the market is much more difficult to access than the beef market. These were very good reasons and they made sense to me. But I’m not the kind of person you can just say no to.

As I understand it, you were basically breaking new ground when you began experimenting with this idea. Could you describe some of the challenges you encountered?
People are the biggest challenge. They were the very first challenge and they’ve remained the biggest challenge. Most folks believe that they’re smarter than a cow and in some ways, we are. But we often don’t take the time to really understand them. So we misuse our intelligence and get misleading results.

As for cows, they’ve basically done exactly what the research said they would do. But like I said, if you’re not watching, if you’re not really paying attention to them, you may not notice that. The best things happen when I’m just paying attention to what the animals are doing and what their responses are to what I’ve done.

In one of the posts on your blog, The Tao of Cow, you mention that you initially struggled to overcome “brush prejudice.” I wonder if you could explain that?
From my perspective, it goes along with overcoming any of your assumptions about a plant. When I was managing goats for fire risk reduction, I was really interested in getting rid of brush. But it was so resilient that it would come back regardless of how many times I treated it. I, like lots of people, thought that brush was a bad thing, especially to have in a pasture. But the reality is that it is really resilient and so you always have forage if your animals know how to eat it and it will always come back. We need to look at invasive plants as potential forage, instead of a potential problem. In the end, we’ll be much better managers, we’ll reduce our costs, and we’ll reduce a lot of our headaches. The only thing that it takes for us to win the weed war is to change our minds. But it’s hardest thing of all to do.

How do you go about changing ranchers’ minds?
Not surprisingly, it’s a very difficult niche market. I started by trying to explain to them how much money they could save if their cattle ate weeds. Then I began putting together all the information about nutritional value so they could compare it to their grasses. I’ve been working with a group of ranchers in Boulder County, Co for six years and last year, one of them finally got it. He kept saying, “I want you to keep good forage in front of my animals.” So I walked him to the pasture and for each weed, I would point out, “This one has 16% protein and the grass next to it has 4% and a cow needs 8%. And at 16% she will gain 2.2 pounds per day.” As we walked through the pasture, he finally got it. And this year, I called him when he was putting his cows out to the pasture and asked him how they were doing. He said, “Oh, they went straight for those weeds.”

It seems as though you’re really straddling two realms – taking primary literature and translating it into management plans. Much of the research has important implications for ranchers but isn’t exactly accessible to someone without scientific training. I’m curious about your approach.
When I first started down this path, I hadn’t spent much time at universities. Just the way they wrote with all of the little citations and footnotes… I found it very unattractive and very difficult to work my way through. I even thought that some of the research they were doing was ridiculous. What I’ve discovered is that you never know which question is going to give you the answer you need for a much bigger problem. I think it’s really important for people to ask, what are the questions that we want to ask and how can we look for the answer?

Do you think that using cows as weed managers is more effective than spraying herbicides?
Definitely. We have yet to eradicate any weed species using herbicide. I saw a presentation in 2008 that indicated that glyphosate (also known as Round-up) becomes less effective as atmospheric CO2 concentrations increase. Not only is the herbicide becoming less effective due to increasing carbon dioxide in the atmosphere, plants are also becoming more resistant to it. From an economic standpoint, if you have to keep spraying the weeds once every five years, that adds a cost per pound of gain to your animal that you will always have. But if you decide that weeds are forage, suddenly you lose that cost per pound of gain. To me, this is a very small piece of a very large system of how we raise our food. And it seems to me that we should do it the easiest, least expensive way possible.

Say you’re a typical Western rancher and you have 400-500 cows. You train 50 of them and within a year they’ll have trained all the rest. The cost of training those fifty cows is about $250 and you’ll never have to do it again. On average, a gallon of herbicide costs $250 and it will treat not nearly as many acres as the cows will. It just makes sense to me.

You know, I spend a lot of time with farmers and ranchers and I have yet to meet a rich farmer or a rich rancher. But I have met many well-to-do herbicide salesmen and supplement salesmen. It makes you wonder if the people that make the most money out of agriculture aren’t the ones that sell these products to farmers.

Looking for more information on training cows to eat weeds? Visit Kathy’s website, The Tao of Cow.

The Training Steps (from Livestock for Landscapes)

1. Know your plant.
Begin by finding out about the nutritional value and the toxins in your target plant. Many weeds are very nutritious, but like all plants they contain toxins. Prevent illness by knowing your toxins.

2. Choose the right animals to train.

Young animals are more likely to try new things. Females also stay in the herd longer and teach their offspring. Train only as many as you can handle. They will teach everyone else for you.

3. Reduce the fear of new foods.
Setting up a daily routine of feeding animals something nutritious but unfamiliar gives them positive experiences with new foods and makes them comfortable trying new foods. Feed them something new twice a day for four days. When you introduce your target weed on the fifth day, they’ll eat it because it’s just one more new thing in their routine of new things.

4. Practice in pasture.
Each new plant requires that your animal learns a new grazing technique. Give them a day or two to practice in small “classroom” size pastures. Then when you send them out in the world, they’ll have the skills they need.

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