In a year with higher than average rainfall, it can be a challenge to find a long enough window of dry weather to make high quality horse hay. These conditions sometimes prompt equestrians to investigate alternative sources of forage.
How are forage crops preserved?
Understanding how forage crops are preserved is the first step in determining what options are available.
The process of hay-making prevents grasses and legumes from spoiling in storage by drying them down to 10-18% moisture. The lack of water prevents mould and bacteria from spoiling the feed. It also prevents the hay from heating. Heating reduces the nutritional value of the hay by damaging sugars and proteins and can possibly start a fire.
Another method of preserving forages is to ensile them (make silage). By eliminating oxygen in forage crops with 45-85% moisture content, naturally-occurring bacteria ferment the sugars in the plants, which drops the pH below 5. Fermentation takes three to four weeks, but the resulting acidity prevents spoiling so long as no air is introduced to the silage. Sometimes descriptive names are used to identify the crop being ensiled; grass silage and haylage are terms used to describe grasses and legumes being preserved this way. If the silage is made into a large bale, it may be called baleage. Because the sugars are used up during fermentation, the forage is no longer sweet, and horses will refuse to eat it.
It is also possible to preserve forage at an intermediate moisture content between hay and haylage. “Wrapped hay” is baled between 20-45% moisture content. To keep this forage from heating, it is wrapped in 6-8 layers of plastic. The wrapping excludes oxygen, which prevents some spoilage. However, this crop is not wet enough to ferment. This means that the sugar content is not reduced, and wrapped hay is still palatable to horses. Wrapped hay will spoil very quickly in the presence of air as it is not fermented. Opened bales should be completely fed within two days.
WARNING: In other English-speaking countries, the term “haylage” is used to describe forage baled at 20-45% moisture content. This is not a fermented feed! When sourcing an alternative forage, be sure to ask about the moisture content at harvest to ensure the feed is palatable to horses. In Ontario, haylage is fermented and many horses refuse to eat it.
Consider available infrastructure
As individually wrapped bales are portable, there is an opportunity for farmers to sell surplus wrapped hay. However, proper handling is critical to prevent spoilage in transit and storage. Tractors need to be large enough to lift bales that could weigh nearly twice as much as a dry hay bale of the same size.
Prongs/forks should not be used to move the bales, as they risk puncturing the plastic that keeps air out; grapple attachments (Figure 1) are designed to pick up wrapped hay without poking holes in the plastic. Even in storage, care must be taken to prevent puncturing the plastic. Prevent access by rodents, birds, and other wildlife to bales of wrapped hay as they will easily damage the plastic wrapping. Horses turned out with the wrapped hay may rub on the bales and tear the plastic. Any holes caused before feed-out can spoil the forage. An entire bale should be consumed within two days of being opened, or it will spoil.
Advantages of wrapped hay
Due to its higher moisture content, wrapped hay is generally not dusty. This can be an advantage when feeding horses with respiratory issues, as the forage does not need to be soaked before being fed.
Cautions when switching from dry hay to wrapped hay
Making the change from dry hay to wrapped hay should be done gradually over a couple of weeks to prevent digestive upset or colic. Wrapped hay is often much richer than dry hay, so the quantity needed to maintain a horse’s weight may be less. This is because wrapped hay is typically harvested earlier than dry hay, when plants are less mature and have higher protein and energy levels. A forage test will tell you the nutritional quality of your wrapped hay, and equestrians can work with a nutritionist to adjust their horse’s diet accordingly. Testing for mould and mycotoxins can alert horse owners to wrapped hay that has spoiled in storage.
One of the biggest reasons that wrapped hay is not commonly fed to horses in Ontario is the risk of botulism. Horses are very sensitive to the toxin produced by the bacteria Clostridium botulinum, which can be found in soil and dead animals. C. botulinum thrives in anaerobic conditions above a pH of 4.5, conditions which occur in wrapped hay. Wrapped hay contaminated with botulism may not appear spoiled. Symptoms of botulism in horses include weakness, muscle tremors, stiffness/stumbling, drooling, loss of control over the tongue, and an inability to eat. Death occurs when paralysis affects the lungs. Horse owners should talk to their veterinarian about vaccinating against botulism before they start to feed wrapped hay. (Wright and Kenney, 2001).
Horses can be fed wrapped hay successfully, but it requires planning and diligence. Take care to purchase wrapped hay that was harvested at the correct moisture and sealed correctly. Before purchase, thoroughly check bales for any signs of damage to the plastic wrap. Do not purchase bales showing signs of damage to the plastic wrap. Protect the wrapped hay from punctures until it is time to feed it. Test the forage for nutritional quality, mould, and mycotoxins before feeding. Work with a veterinarian to vaccinate against botulism before switching to wrapped hay and be sure to feed a bale within two days of opening it. When managed carefully, wrapped hay can be quality forage for horses.
Dr. Bob Wright and Dr. Dan Kenney, 2001. Botulism in Horses and Haylage. OMAFRA.