BEEF Daily

3 Things You Need To Know About Feeding Moldy Hay


Moldy hay poses a risk to horses, cattle and people. Here’s what you need to know. 

A few years ago, we had a very wet summer. Among the positives were that the pastures grew wildly, and the hay fields were lush with new grass to cut. The biggest negative, as you might guess, was that our cut hay often got rained on or we had to bale it before it was sufficiently dry because more rain was on the way. The result? Moldy hay.

We didn’t have much choice but to gamble and feed the moldy hay, but we tried to manage around it where we could by diluting it with good hay as much as possible. However, we paid a price for that decision with multiple abortions that winter.

I recently read an article featured in Bruce Anderson’s Hay & Forage Minute that got me thinking about this topic. Although we have lucked out with timely rains and drier summers the past couple of years, we still get a random abortion here and there, and it begs the question about whether the hay caused the problem.

Anderson, who is a University of Nebraska Extension forage specialist, writes, “Moldy hay. No matter how hard you try, eventually you have mold in some of your hay and need to decide about feeding it. Feeding moldy hay to livestock is a tough decision.  Although all hay contains some mold, when mold becomes easily noticeable, the decisions become important.

“Usually, mold makes hay less palatable, which can result in lower intake or even in animals refusing to eat the hay. Many other problems from mold occur because of mycotoxins produced by certain mold fungi. This also is part of the decision problem since not all molds produce mycotoxins, and the amount produced by those that do is unpredictable.”

I rounded up three direct negative effects of moldy hay from Anderson’s article.

Here are the risks of feeding moldy hay to livestock:

1. Horses are impacted the most by moldy hay and can lead to respiratory and digestive problems like colic or heaves.

2. Cattle aren’t as sensitive to moldy hay, but certain molds can result in mycotic abortions or aspergillosis.

3. Moldy hay also puts ranchers at risk. Mold spores can cause “farmer’s lung,” which results in the fungus growing in the lung tissue if it has been inhaled.

Anderson recommends that feeding moldy hay should be minimized as much as possible to the more sensitive animals like horses and pregnant cows.

Mold is a difficult problem to deal with. Common sense and good observation often are your best decision aids,” he concludes.

Have you ever had issues with moldy hay? What do you do with your forage if you have discovered a mold issue? Share your thoughts in the comments section below.


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Discuss this Blog Entry 9

Kent Hanawalt (not verified)
on Jan 13, 2014

I deliberately bale hay - in small squares - at a moisture that might be considered dangerous in big bales.
I wait until the hay is dried through, then go out at night to catch the humid air that toughens up the leaves. A moisture tester at that time would measure too high.
So I shoot for a final moisture between 20% and 25%. But I would simply not bale anything I thought would mold from INTERIOR moisture.

Our problem this year is that we've had so much late rain and snow that the top bales of the stack are moldy from EXTERIOR moisture.
I simply feed enough hay that the cows can nose through and leave the stuff they don't like. That spreads the bad hay back on the hayfields.

Spring will tell, but there is no evidence of abortion so far.

gray hair head (not verified)
on Jan 13, 2014

The blue mold is undesirable but the white stuff be very cautious about even thinking about feeding it.

Bob Voegeli (not verified)
on Jan 13, 2014

If I know the hay is moldy before I feed it, I will feed moldy hay by spreading it on the ground. The cattle will eat some and the rest is worked into the ground. I do not put it in the hay feeders with good hay.

Peter Franzky (not verified)
on Jan 13, 2014

Molds and bad yeasts are poisons, very davistaing to animal and human health and immune function. This needs to be taken very siriously at all times. Dilution is part of the solution. Feeds need to be tested for molds and yeast count (coliform units/gram of feed) and specie indentification prior to feeding. Mold inhibitors and Toxin Binders need to be implemented in those feeds. Ther are many good products on the market.

Ed Fowler (not verified)
on Jan 13, 2014

Prevention of mold is an easy variable. An old rancher friend who was a descendent of a ranching family that had been putting up and feeding hay for many years said mold had never been a problem for him, all he did was salt the top hay bales in his stack. "A hand full of salt on each top bale and no matter how much rain you would not have mold.
He never covered his hay stacks.

I found he was right, I even salt the ground where the hay will be stacked.

His grandfather had build a "salter" that would trickle a little salt into the hay as it was baled, he said it worked great preventing mold, but you had to be careful to clean out the baler after each cutting or the baler would rust badly.

When I first started ranching, the Vet. warned me about feeding moldy hay and blamed everything from pink eye to foot rot on moldy hay. I carefully sorted out all moldy bales and placed them in a pit to burn them later. My cows crashed into the stack moldy hay and ate it. I knew they would all die, but not one showed any sign of 'mold poisoning' - I have not worried about it since.

on Jun 29, 2014

How much salt do you use per bale? I'd love to try this because we get bucketfuls of rain every year, and our hay goes moldy. Do you find it damages the ground below so that nothing will grow?

on Feb 7, 2015

Would this be regular table salt? Just sprinkle on top of bales as I stack them? On the ground as well? Thank you for sharing such a great method.

JB (not verified)
on Jan 17, 2014

We have fed moldy hay some days worse than others. Never had a problem which could be traced to it. You don't like doing it but sometimes that is what you have. More problems with heavy cows slipping on icy feed grounds.

Anonymous (not verified)
on Jan 20, 2014

My hay is fine. But the problem I had is the last field the cows were in the corn was done quite bad and had mold on the ears on the ground which the cows ate. I thought I was treating pneumonia, but the vet said it was from the mold the cows consumed in the last trimester,the calves were slow and lifeless. We are treating for a gut problem and working through it.

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BEEF Daily Blog is produced by rancher Amanda Radke, one of the U.S. beef industry’s top social media “agvocates.”


Amanda Radke

Amanda Radke is a fifth generation rancher from Mitchell, S.D., who has dedicated her career to serving as a voice for the nation’s beef producers. A 2009 graduate of South Dakota State...

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