How Can You Tell If Hay Is Moldy?

Horses are very sensitive to moldy hay, and even though some scholarly information will tell you that a certain amount of mold is safe to feed, you are better safe than sorry. When you examine hay, if you can see or smell mold or feel dampness, you should not feed that hay to your horse.

When you purchase hay from a feed store, you will not be able to break open bales, but the store owner or buyer should have examined a test bale of hay before paying for the current load. When purchasing hay a bale at a time like this, you can usually take the bale back for exchange or refund if you get it home and find that it is moldy or has some other problem.

If you are purchasing hay in bulk, you must take the responsibility of examining a test bale yourself before making your purchase. If you order hay to be brought to you, examine a test bale before accepting the shipment.

You would do this by breaking the bale open and examining it with your own senses of sight, smell and touch for signs of mold. These are:

  • An overall grayish appearance
  • Gray, black or brown growth
  • A musty smell
  • Dampness

If you can see any of these things, don’t buy or accept that hay.

How To Identify Moldy Hay

Why Is Some Hay Moldy?

If the weather is very damp, or you had a very rainy season while the grass was growing in the field, grass may have mold on it when it’s cut for hay.

If the hay is not dried properly, it may be moldy when it’s baled.

If the hay is not stored properly mold can grow on it.

Keep all of these things in mind when making a hay purchase.

What’s The Best Way To Prevent Mold On Hay?

Best Way To Prevent Mold On Hay

Once you have made a good hay purchase, avoid pouring your money down the drain by storing your hay properly. Don’t just set it outside with a tarp over it because this will allow moisture to get in, and the tarp will prevent moisture from evaporating.

Ideally, you should store your hay inside in a sound structure that will not allow moisture to get in. Don’t store it directly on the ground. Instead set it up on pallets.

Stack your hay in an alternating manner with a little bit of space between bales so that air can circulate among the stacked bales.

Don’t stack all the way to the ceiling, and don’t put a tarp on top. Your hay needs space above for air to circulate and moisture to evaporate.

You may wish to place a dehumidifier or a fan in your hay storage structure to reduce moisture in the air and keep the air circulating.

Feed Hay Responsibly

Feed Hay Responsibly

When you feed your hay, don’t feed too much. Feed only as much is your horse will eat in one feeding, unless you are using a hay net or other type of slow feeder. Be sure to place this type of feeder in a location where it will be at least somewhat sheltered from rain and will have ample air circulation around it to prevent mold from growing on the hay.

It’s also a good idea to place your hay in such a way that your horse can graze on it naturally. Place it low enough so that he is reaching down to access the hay. This will help prevent any mold spores that may be present from entering your horse’s nasal passages and causing respiratory distress.

If hay is dusty, it may also be a bit moldy. When this is the case, you can soak the hay for about half an hour and then rinse it before presenting it to your horse. This will prevent having your horse inhale moldy dust. This practice also reduces the sugar content of hay, so it’s a good thing to do for horses that may have metabolic problems.

Is There A Sure-Fire Way To Know Hay Is Safe?

The only sure way to find out if your hay is moldy is to have it professionally tested. You would do this by sending it to a forage testing laboratory and having them analyze it for a fee. This is usually about $40.

No matter how good your hay is, it will have some mold in it because mold is ubiquitous and there’s just no getting away from it. Having your hay professionally tested can tell you exactly how much mold, and what type of mold, is present.

This PDF document from the University of Wisconsin Extension contains a handy chart that lets you know what levels and types of mold are safe or unsafe for feeding horses.

Nicky Ellis
Nicky has been an editor at Horses & Foals since 2017. Horses have been in her life from her earliest memories, and she learned to ride a horse when she was 5. She is a mom of three who spends all her free time with her family and friends, her mare Joy, or just sipping her favorite cup of tea.


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