Basics of Hay Storage

Oat hay carefully stored in a barn
Oat hay carefully stored in a barn

Hay Quality Is Affected by Moisture, Temperature, and Time

It goes without saying that you want to feed your horses the best quality hay possible, whether you grow your own or purchase the hay. Unfortunately, hay begins to lose quality as soon as it is cut, even under the best of storage conditions.

Molds and bacteria, which thrive under warm, moist conditions, consume many of the nutrients contained in hay, and the longer these conditions exist, the more damage is caused. In addition, weather conditions and rodents can wreak havoc on stored hay.

 Protecting hay to maintain nutrients

Protecting hay to maintain nutrients

Hay begins to lose quality as soon as it is cut, even under the best of storage conditions, but by keeping bales in a compacted state so open hay is not exposed to air you maintain better quality.">

Another important consideration in all hay storage is the prevention of fires, whether hay is stored inside or outside.

Prevent Dry Matter Loss and Preserve Forage Quality

Timing of baling of hay is critical for maximizing its feed value Most experts maintain that the optimum moisture content for baling is in the range of 15% to 20%, especially for alfalfa because leaf loss increases as moisture decreases. If hay contains more than 20% moisture, the chances of mold increase. Also, dry matter and nutrient loss are increased and more discoloration occurs.

Dry matter losses result from microbial activity, weather deterioration, and continued plant respiration. At low moisture levels, this loss will be minimal, but as moisture levels increase above 20%, mold growth and dry matter losses become greater. The increased microbial activity results in additional heat that creates more dry matter loss, and in some cases, may lead to destructive fires.

A field yielding nutrient-rich hay

A field yielding nutrient-rich hay

Harvest conditions play an important part in hay quality.

Harvest conditions play an important part in hay quality

Weathering or climatic conditions create further dry matter loss. Rain water can leach out the more soluble digestible nutrients. Rain damage of field-cured hay and of hay stored outside can result in anywhere from 5% to 50% dry matter loss.

Storage conditions can have a dramatic effect on the amount of crude protein, soluble carbohydrates, and digestible dry matter contained in hay. In addition, palatability can be greatly affected when hay is not stored properly.

Forage quality losses that affect the chemical composition and feed value of the hay occur with both inside and outdoor storage, although more feed value is lost with outdoor storage. The amount of available crude protein remains much the same with both kinds of storage, but highly digestible soluble carbohydrates decline with weathering. The loss is greater for legumes than for grasses.

Outdoor Hay Storage

  • Choose a well-drained, elevated storage site in a sunny location, preferably in an area where frequent breezes occur
  • Choose bales or baling procedures that create well-formed, tight bales with a minimum of 10 pounds of hay per cubic foot in the outer inches
  • Place bales on pallets, coarse gravel, or old tires rather than directly on the ground to protect from losses caused by ground moisture
  • Stack bales in closely butted rows with a gap between rows. The space between rows allows for air circulation and sunlight penetration
  • Cover bales with heavy plastic sheeting, a tarp, or other fabric covering that is firmly secured to prevent wind from blowing it off. Leave flat ends of outside bales, as well as a few inches along the sides of rows, uncovered to allow moisture to escape and air to circulate
  • Make sure there are no objects near hay that would attract lightning. Reduce fire risk with a no-vegetation zone at least 3 feet in width around the storage area
  • Feed hay stored outside before feeding hay stored inside
  • Stack bales so older hay will be fed first. Feed value losses for hay stored 12 to 18 months can be twice as great as losses for hay stored 9 months

Indoor Hay Storage

  • Keep the hay off the floor by storing it on pallets
  • Keep hay dry by making sure no roof leaks or water drainage problems exist and that any condensation that accumulates on the inside of the roof is minimized or channeled away from stored hay
  • Stack hay for maximum air flow.  Bales should be stacked in closely butted rows with a gap between rows for air circulation
  • Keep bales in compacted state so open hay is not exposed to air that will cause it to lose quality
  • Rodent-proof your storage area by plugging any entrances with steel wool and keeping an eye out for signs of rodents that might contaminate your hay
  • Reduce fire risk by storing hay at proper moisture levels, which should be no more than 18%, and by stacking bales so adequate air movement and ventilation can occur
  • Stack hay so you will be using older hay first

Prevent Hay Fires

When hay that has more than 20% moisture is packed tightly in bales which are stacked close together, the growth of organisms that generate heat can increase hay temperatures to the point that chemical reactions take over, resulting in fire danger when temperatures exceed 150 degrees F.

Hay as a combustible

Hay as a combustible

When hay with more than 20% moisture is packed tightly together, organisms that generate heat can increase temperatures so chemical reactions occur resulting in fire danger; if the temperature reaches 180 degrees, call the fire department and move all animals from the area.

If conditions are right, and you suspect that heat may be building up in your stored hay, you should take steps to measure the temperature.

An easy way to monitor the temperature is by driving a 1/2 to 2 inch pointed pipe into a hay bale. Tie a thermometer with a piece of string and lower it through the pipe. Wait 10 to 15 minutes for the thermometer to register an accurate temperature, then pull it out and read the temperature. Repeat with several bales.

If you don't have a thermometer available, simply drive the pipe into the bale and remove it after 15 to 20 minutes. If the pipe is too hot to hold in your hand, the fire danger is critical.

If the temperature is below 140 degrees F, little danger exists. If the temperature is between 140 to 150 degrees, check bales daily. If the temperature rises above 160 degrees, move the hay from the building and spread it out to cool.

If the temperature reaches 180 degrees, call the fire department, move all animals from the area, and, with fire equipment on hand, remove bales to the outside and place in rows for easy access. If bales ignite, soak with water, forcing the water into the center of the bales.

Once the temperature drops below 100 degrees, it is safe to move the hay back into the building.

Improving Hay Storage Will Make A Difference

By taking time to assess your hay storage situation and making any necessary adjustments, not only will you prevent dry matter loss and maintain forage quality, but you will also save time, effort, and money, along with having healthier horses.

About the Author

Flossie Sellers

Author picture

As an animal lover since childhood, Flossie was delighted when Mark, the CEO and developer of EquiMed asked her to join his team of contributors.

She enrolled in My Horse University at Michigan State and completed a number of courses in everything related to horse health, nutrition, diseases and conditions, medications, hoof and dental care, barn safety, and first aid.

Staying up-to-date on the latest developments in horse care and equine health is now a habit, and she enjoys sharing a wealth of information with horse owners everywhere.