How Weed Control in Pastures Affects Horse Health

How Weed Control in Pastures Affects Horse Health

Pasture Management

Every agricultural program in the United States has a class on Pasture Management. It’s an important topic especially when it comes to maintaining horse health. When you have a finite amount of land to use for grazing animals, it is important that you know how to maintain the health of the land so you can maintain the health of the animals grazing on that land. You also have to be mindful of your neighbors, who most certainly would not appreciate it if your thistle problem became their thistle problem.  

Today’s equine pasture typically has three to five blends of grasses. These are recommended by equine nutritionists based on the National Research Council’s minimum daily requirements for maintaining horse health, but there is also consideration for control of invasive species to protect commercial agricultural production. Landowners work hard to limit invasive weeds and often remove hedgerows and thorny bushes to keep the horse from eating those things not on a program list.

Weed control in the horse pasture: 

When I was a child, we walked the bean fields. “Walking the bean fields” was not a metaphor for a mechanical process that was scheduled to take place. This literally meant that we would walk the rows of a bean field and pull weeds. Many of today’s small organic farmers still walk their fields, or they use natural weed inhibitors to control weeds, but large-scale producers typically control weeds with chemicals like glyphosate (Round-Up), 2,4-D, Dicamba, or a combination of thereof.

The National Institutes of Health (NIH) website has an abundance of solid research that tells us that glyphosate, most commonly known as Round-Up, kills cells, is a probable human carcinogen, disrupts digestion of key nutrients, and more.  Glyphosate is also known to reduce the number of “good” bacteria that act to control the “bad” bacteria in the gastrointestinal tract of horses, which may lead to gastrointestinal diseases.

For example, members of the clostridium family  are present in the gastrointestinal tract of the horse. The “good” members act to protect the gastrointestinal tract from invading bacteria and release compounds to support proper immune health and balance in the gut. The “bad” members of the family are linked to gastrointestinal disease. Overgrowth of the bad members is controlled by lactobacillus, lactococcus, streptococcus, pediococcus and enterococcus. Glyphosate acts to reduce or eliminate all of the bacteria within this helpful group, which allows disease processes to take hold. 

Dicamba and 2-4-D were increasingly combined with glyphosate as weeds became resistant to glyphosate’s deadly effects. Calls and complaints from farmers about the effects of Dicamba on their crops, their livestock and their health grew at an alarming rate. The Dicamba papers illuminate the serious issues associated with the use of this chemical and its partner poisons. 


2,4-D is in a class of compounds called endocrine disruptors. These are chemical compounds that mimic or inhibit the body's hormones. Laboratory studies suggest that 2,4-D can impede the normal action of estrogen, androgen, and thyroid hormones. Dozens of epidemiological, animal, and laboratory studies have shown a link between 2,4-D and thyroid disorders. This is important because our thyroid works to ensure proper development and function of the brain. It is important to note that 2,4-D doesn’t deteriorate but sticks around in the environment. In 2014 the EPA estimated that 46 million tons of 2,4-D was used in the United States.


How does the U.S. government decide to approve, ban or further investigate safety of chemicals used to grow and manufacture our food? I reviewed the EPA website and found the following:

“How Did The EPA Assess the Safety of Enlist Duo?”

With Enlist Duo's large body of scientific information.”  

In other words, Monsanto/Bayer provided the U.S. government with the information necessary to allow the FDA to approve the use of their chemical applications. If Monsanto/Bayer deliberately provided misinformation or failed to provide facts that would disallow sales of their products, the U.S. regulatory agencies would not know it because they did not conduct their own independent research. Research done by the NIH, while available, is ignored.

There is hope for change in the horse feed industry, and there are simple things we can do to improve horse health. I’ll touch on that in my next blog. 

~ From the desk of Mary Hartman, CEO and Founder

*This is a personal blog. Any information herein is not to be construed as medical advice.