How To Tell If the Hay is Moldy? How to Fix It?

Hay is far more nutritional than any other horse feed but it is usually avoided because it develops mold quickly and can not be stored for a prolonged time. As the unfavorable weather and storage conditions can easily contribute to the development of mold, it’s quite fair to ask “how can one tell if the hay has turned moldy?” Well, the mold is never hideous, it can be caught by it’s signs.

Fortunately, even a naive person can easily catch it happening and destroying the hale bale. In this article today, we would be discussing the common signs of mold development, it’s treatment and prevention. So, none of my readers has to keep a reserve to buy an extra bale of hay just because the previous one gets moldy. Let’s not beat about the bush and come to the point;

How to tell if the hay is moldy?

First of all, your concern is valid when you have to store hay for uninterrupted nutrients supply. You can mainly judge the moldy hay by the appearance and smell. There would be some other signs as well but the moldy smell would alarm you more than any other sign of mold. 

All possible signs of moldy hay

When the mold starts spoiling the horse feed, it shows visible signs of it’s appearance. The signs are;

  • Smell
  • Unusual color
  • Excessive dust
  • Dried-out appearance 
  • Excessive heat coming out from the center of the hay bale
  • Presence of mold spores


When a fruit or vegetable gets moldy it starts to smell strange; moldy. The same is the case with hay, the hay once it has developed even a bit of mold, would not smell normal at all. To be able to judge the hay by it’s smell, you need to know how the fresh hay smells.

The fresh hay would have a sweet woody smell. Smelling fresh hay would also remind you of maple syrup as it also, at the same time, smells like it as well. Whereas the moldy hay would have an acrid or musty smell. Moreover, you can also call the hay moldy when it starts smelling dusty. 

Pro tip

It’s hard for a naive person to judge the quality of hay by it’s smell even though he/she does have a nose to sniff. It is suggested to cut the bale from the center, try sniffing immediately(without even wasting a second) because if you allow it to remain open for a minute or two, you may never be able to judge it from the smell as the surrounding air dilutes the odor. 

Unusual Color

You can not judge the book by it’s cover but you can judge the hay by it’s color or appearance. Even before smelling the acrid or musty smell, the unusual color would explain you all. The fresh or rightly preserved hay would have bright green color whereas, the moldy hay may appear in pale yellow or brown color. So, we can say the color change is the biggest indicator of mold. 

Excessive dust

The moldy hay would not only have a dusty smell, but it’s also going to be bombarded with dust as well. According to Research, the good-quality or let’s say fresh hay can also be slightly dusty but the moldy hay would have enough amount of dust to be called dusty. 


Dried-out appearance 

Hay, that can still be fed, would look and smell fresh. The bright green color and sweet fresh odor are the visible signs of good quality hay. The hay that gives a dried-out appearance usually indicates the presence of mold. So, be aware! 

Excessive heat coming out from the center of a hay bale

The hay that gets moldy or starts developing mold releases excessive heat from the center. Usually, when the hay that is not ready to be baled is baled, the hay bale starts developing mold and producing heat. So, whenever you find excessive heat releasing from the center, even if you can not spot any mold spores, take it as a red signal. 

Presence of mold spores

The presence of mold spores is the most authentic identification of moldy hay. The mold spores can be any color including grey, white, green, brown, purple, pink, yellow, red, orange. Besides the individual colors, the mold spores can appear in a combination of colors as well. The mold spores can easily be noticed but in a hay bale, you have to look thoroughly to spot these visible marks of identification. 

The moldy hay would be pretty “obvious”, if it still can not be identified, one can look for these above-mentioned signs. It’s super important to bring fresh hay as the moldy hay can cause colic, respiratory issues, and in serious cases become a reason for the horse’s death. (Source)

So, be aware! The hay should be bright green, sweet in smell, soft and pliable to touch, and must have consistent temperature throughout hay bale. 

Read also How Many Alfalfa Cubes Equal a Flake?

How to fix moldy hay? 

Horse enthusiasts, all around the world, usually face the moldy hay issue every other day. We have seen several of them struggling to prevent and fix this issue.

Moldy hay can not be completely fixed and safe to fed. Removing the affected parts and feeding the unaffected ones can minimize the loss but it’s would be quite risky. As the hay that is not completely taken down by the mold can not be considered fresh and nutritional at all.

So for the record, moldy hay can not be fixed it can, however, be prevented. Once the hay gets moldy removing the affected parts, picking out, and feeding the unaffected ones is the only solution. 


How to prevent mold development? 

Fortunately, careful behavior can prevent mold to a great extent. The horse enthusiasts can easily prevent this annoying issue by following these below-mentioned tips;

  • The mold usually develops when the hay is left to rain on or to tolerate the wet and humid conditions. So, the one effective way to prevent mold is to store hay in dry places. It is also recommended not to buy in bulk as it is perishable and prone to developing mold. 
  • The bale that is not properly dried out usually ends up developing mold. Allowing hay to dry out or lose the moisture content naturally is another easy way to nip the evil in the bud. You can use any hay streamer too here is our complete guide on Best Horse Hay Steamer 
  • Not storing hay for a prolonged period would also help you in relaxing out a bit. As this nutritional powerhouse is super perishable, practice FIFO(First-In-First-Out) method to prevent this problem from happening in the first place. 


Hay can easily get moldy due to unfavorable weather and storage conditions. It is suggested not to feed moldy hay to horses as moldy has been reported causing colic, respiratory problems, and even unalarmed deaths.

The moldy hay can be judged by an acrid or musty smell, unusual brown or pale yellow color, dried-out appearance, excessive dust content, and inconsistent heat throughout the bale.

The moldy hay can not fix completely, you can only throw away the affected parts and feed out the rest immediately. It’s true that the ” mold issue” can not be completely fixed but it can be prevented. To prevent it from happening, do not buy in bulk, store in a cool and dry place, and use the FIFO method.


Hi, I am Waqar and active in the horse world since 2012. I have MSc (Hons) in Agriculture from the University of Agriculture Faisalabad. I love to solve equine health care issues and note down in the form of research papers. I have written hundreds of equine health care, accessories, names, and history-related blogs. My equine related work is watering a lot of horse-related magazines and blogs.

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