Leafy spurge (Euphorbia esula) infests rangelands and pastures in all but the southern U.S. and is found throughout Canada. It is considered a noxious invasive species everywhere it turns up thanks to the extreme difficulty we have in controlling it. It spreads via seeds and rhizomes and there is some evidence that it changes soil chemistry in its immediate vicinity so that other plants can’t grow. But what most farmers and ranchers living with this plant don’t know is that cattle can eat it without harm, and since its nutritional value and digestibility compares to alfalfa, managing it through grazing could be great for cattle and the bottom line.
Does Leafy Spurge Harm Cattle?
The short answer is “No, it doesn’t, as long as cattle have access to a variety of other forages.” But let’s talk about this more.
When I first started teaching cows to eat weeds in 2004, I had heard a lot of the same information that you may have heard. Sheep and goats can eat it but cows can’t. The sap can cause irritation or burning in the mouth and digestive system, skin irritation and diarrhea. This basic sentence is included in most texts on leafy spurge. On the other hand, I knew that cows on the Rex Ranch in Nebraska were eating spurge. Ranch Manger John Young said they discovered this after marking spurge to be sprayed once the cattle had been moved to a new pasture. When they returned, the spurge was grazed to the ground. Young thinks that their high-intensity, short duration grazing system may have encouraged the cattle to try the weed, and since it doesn’t grow in monocultures there, cows can mix it with other forages, reducing any potential harmful effects.
What I’ve learned since I first trained cows to eat leafy spurge in 2004, is that Young is absolutely correct about the importance of mixing forages when it comes to getting cattle to successfully eat leafy spurge. In 2004 I trained a small herd of heifers (and one steer) to eat leafy spurge as part of my first effort to figure out the steps to teach livestock to eat new foods. They ate leafy spurge well in training, and suffered none of the harmful side effects listed above. When I took them to pasture, I found that in pastures with more variety (grasses, thistle, goldenrod, knapweed, wild roses, and small brush) the cattle ate much more leafy spurge than in of primarily grass. In another training in Montana, in a pasture that was primarily leafy spurge with a small amount of grass, that cattle ate much less leafy spurge.
Here’s What Some Other Folks Found When They Trained Their Cattle To Eat Leafy Spurge
In 2007, Lester Pryce, Saskatchewan’s Prairie Farm Restoration Administration Community Pasture Land Manager, watched my DVD at a meeting and decided to try my training process himself with some Angus heifers and leafy spurge. Since he didn’t have all the instructions, it took him a bit longer, but he had success. He was surprised at the willingness of the cattle to eat spurge in training and at calf behavior. “If green crested wheat and leafy spurge were put in a tub, often the calves would eat the spurge and leave the grass.” When the cattle were left to graze a 30-acre pasture to 50% utilization he found that every leafy spurge plant had been grazed to some degree.
Pryce said of his experiment, “We learned that it is definitely possible to train cattle to eat new foods using Kathy’s cattle training process, and that there may be a possibility for producers to develop a very low cost method for training cattle to consume problematic weeds on our rangelands.”
Here’s an email I received from Silena and Warren Koster of Clinton BC,Canada:
Subj: B.C. Cattle Co. LTD Heifers loving Leafy Spurge
We just wanted to fill you in on our progress with teaching/introducing weeds to our cattle. It WORKS!!!!!!!!!!!!!!!! My husband Warren set about in June with the replacement heifers and a small group of 1st time calved heifers and their calves, to introduce the leafy spurge. It was so lovely to see the cattle bucking and twisting, racing to him and the feed tubs. It took no longer than 7 days. The heifers are now in an enclosure of leafy spurge/grasses/shrubs with their bulls before turning out on range. We are so enthused by the simplicity of the whole idea, and how cooperative the heifers were about it. Thank you for all your dedicated research in this study and passion on your knowledge to others. My daughter, Camilla, and I attended your seminar in Williams Lake, last year.
Sue Kennedy of Kennedy Ranch in Lamoille, Nevada Documented her training on their Facebook page. Click the picture to see it in a readable size
So Why Do Think Cows Can’t Eat Leafy Spurge?
Just like you, I hear it that it’s a problem from scientists, researchers, extension agents and all kinds of people I truly respect. Why are they mistaken?
One reason may be the same thing that makes science so good: reliance on the works and information of others. In this case, all the citations I found eventually pointed back to one source, the 1939 “Poisonous Plants of the United States” by Walter C. Muenscher who related a story of leg hair loss on horses working in spurge infested grain fields. He provided no citation for this story, which has been repeated numerous times, thus I wonder if we started with inadequate knowledge.
Another reason that science is wrong about leafy spurge is that we haven’t always understood the important role variety plays in allowing animals to process nutrients and toxins. Thus, in some experiments, cows were “overdosed” with spurge. When they got diarrhea or went off feed, it was attributed to the weed, not the quantity or lack of variety.
Finally, sometimes we have too easily taken the cow at her word. If she doesn’t immediately eat something, we have assumed it is unpalatable without taking into account the role of learning and neophobia in animal diet choices. It would be like me saying, based on my observations, that only macaroni and cheese and hotdogs are palatable to 4-year-olds.
One last point: in my search to find out why leafy spurge was so harmful I found a paper by scientists who actually looked for the harmful effects supposed to be caused by leafy spurge sap. They found no lesions in “nasal passages, oral cavity, tongue, esophagus or viscera” of animals who had eaten leafy spurge.
The training process I developed to teach cows to eat weeds like leafy spurge is based directly on the discoveries of many dedicated scientists, so I would never suggest that we ignore their information. Rather, when something doesn’t add up to what you’ve observed, it’s time to look more closely, read more, and share what you’ve learned with others. In the words of Mark Twain, “It ain’t what you know that gets you into trouble. It’s what you know for sure that just ain’t so.” Maybe it’s time for us to take another look at what we thought we knew for certain about leafy spurge.
Want Your Livestock to Add Weeds to Their Diet? Our article “How to Teach Livestock to Eat Weeds” will give you the basics.