How to Safely Change Your Horse's Hay

How to make hay changes safely and effectively

“Thou shalt make all feed changes gradually,” could be listed as one of the 10 commandments of horse ownership. The National Research Council’s Nutrient Requirements of Horses: Sixth Revised Edition (2007) states that owners should make any changes in the amount or form of a horse’s feed—grains, concentrates, hay, and pasture—­gradually due to the animal’s sensitive digestive system. This reduces risk of colic due to digestive upset. But sometimes things don’t work out as planned and you need to make a quick switch. Let’s look at scenarios that might call for a sudden change in hay type and how to make the shift safely and effectively.

Dwindling Supply & Changing Demand

Weather plays a critical role in hay production. Each grass and legume species requires a specific temperature and precipitation range for optimum growth. For example, orchardgrass grows best at soil temperatures of 50-65 degrees Fahrenheit with about 18 inches of annual rainfall. In years when growing conditions for plants are challenging, horse owners could find the hay supply drastically reduced. The most common weather-related reason for hay shortages across the world? Drought.

Drought occurs when a high-pressure system locks in over a geographical area, causing below-normal amounts of precipitation. The worst drought in U.S. history, known as the Dust Bowl, caused major agricultural damage in the 1930s. More recently, in New South Wales, Australia, a severe drought with some of the lowest rainfalls on record caused hay prices to more than double, leaving farmers unable to feed their livestock.

Too much rainfall also affects hay production. “Wet weather at harvest can reduce quality by enabling mold growth and dust to form in the hay,” says Christine O’Reilly, MS, forage and grazing specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA).

Basic supply and demand also impact hay availability. “If small square bales are the desired product, one may have difficulty locating them in areas where farmers have switched to (producing) round bales, as they are less labor-intensive to produce,” says Alison Moore, DVM, DVSc, Dipl. ACVIM, ACVSMR, lead veterinarian of Animal Health and Welfare with OMAFRA.

If hay ships from Ontario, for instance, to other parts of Canada or areas of the United States that might be experiencing a drought, Ontario’s hay supply will dwindle. Basic economics tells us that when there’s a low supply of a ­commodity, there’s increased demand leading to inflated prices. If hay quality becomes a problem, more people switch to alternative forages, reducing baled-hay demand.

Even with a plentiful hay supply, some health conditions might necessitate a change in hay type. For instance, switching to alfalfa could help a horse with gastric ulcers. In fact, researchers have shown that feeding horses alfalfa hay could provide acid-buffering support by increasing stomach pH. Injuries, especially those to the teeth or jaw, can negatively affect a horse or pony’s ability to chew long-stemmed hay properly, necessitating a processed, chopped hay; hay cubes; or pellets. Then there are the unavoidable natural changes that warrant a forage change. As horses and ponies age, they lose the ability to chew and digest ­long-stemmed forage as easily as their younger counterparts. That’s because after about age 20 their teeth stop erupting and can wear down to the gumline. Cheek teeth surfaces flatten and smooth out, diminishing their ability to chew forage properly. Some older horses might even lose teeth or suffer from dental disease, affecting their ability to chew, as well.

Colic Concerns

Although more typical when making rapid changes in grain or concentrates, colic risk increases with changes in hay type, too. Among all the feed changes studied in horses, those to hay type remain the most significant. Based on data from practicing veterinarians in Texas, Noah Cohen, VMD, MPH, PhD, Dipl. ACVIM-LA, director of the Equine Infectious Disease Laboratory at the Texas A&M University College of Veterinary Medicine & Biomedical Sciences, in College Station, says horses experiencing a change in hay type were almost 10 times more likely to colic in a study of 1,030 colic cases than equal numbers of controls. The most common colic causes associated with changes in hay type include impaction or changes in microflora altering pH or volatile fatty acid ­production, he says. 

How to Safely Switch Your Horse's Hay

Quick Hay Switch Tips

Things happen, and even the best plans can fail. So how can you make a quick hay switch safely when you’re in a bind? Blend as much as possible.

“I would recommend trying to mix in new with old hay over several days to gradually transition over to new hay,” says Cohen. Use a haynet to help blend the new and old hay and prevent horses from sorting and wasting.

Completely out of hay and can’t transition? Cohen recommends feeding smaller amounts of the new hay frequently (i.e., small, spaced-out hay meals throughout the day). “Ensure the horse has access to plenty of water, and try to avoid other putative risk factors for colic, like transportation and heavy exercise, during the transition,” he says.

Watch for signs of digestive upset such as colic and diarrhea. Cohen recommends carefully monitoring fecal output, consistency, and appearance. “How much fecal output, is the feces adequately moist, is it formed, does it have mucus on it (causedby prolonged transit time through the intestinal tract)?” he asks.

Alternative forages and fiber sources, along with supplemental concentrates, can help owners stretch their current hay supplies. In addition to the times when hay quality is low, when prices are high, some horse owners switch completely from baled hay to the alternatives, such as hay cubes, hay pellets, roughage chunks, or haylage (also called wrapped hay).

O’Reilly notes that while most horse owners are familiar with how to feed baled hay, many do not know how to properly select and feed alternative forages.

“It is important to only purchase haylage or wrapped hay with a moisture content between 20% and 45%,” she says. “Anything higher in moisture may be unpalatable to horses” and can cause mold growth.

Botulism is also a risk for horses eating haylage, so veterinarians recommend vaccinating these horses against this deadly neurologic disease. “Asking the producer for references of horse owners that have bought their product and a copy of the forage analysis may put one’s mind at ease,” says Moore.

Make the change from baled hay to an alternative forage or fiber source under equine nutritionist and/or veterinarian supervision, if possible, because the diet will need to be balanced for the horse’s stage of growth, reproductive status, and activity level, as well as any ongoing medical conditions such as equine metabolic syndrome or dental disease. Moore recommends feeding at least 1% body weight of forage (ideally 1.5-2% body weight) with the total amount of feed consumed equal to about 2.5-3% body weight.

“The alternative forage (hay cube or hay pellet) should be the same hay type as the hay,” she adds. “For example, if timothy hay is being fed, a timothy hay cube should also be fed.”

If possible, save the best-quality hay and allow older horses, growing horses, and those most prone to colic or digestive upset to have the longest transition from old to new hay.

How to Safely Switch Your Horse's Hay

Stretching Hay Supplies

Putting hay-saving techniques into practice can help reduce waste and extend supply both now and during periods of hay shortages. Here are some tips for storing and feeding square and round bales effectively:


After baling, and once the bales have reached the proper moisture level (about 15% or less), producers should move them into storage as quickly as possible to prevent weathering. The biggest hay losses occur in storage. Keeping hay outside, whether in the field or elsewhere, can cause large dry matter losses, more so for round than square bales. Leaving bales outside exposes them to the elements, which causes nutrient leaching and spoilage (called weathering). While precipitation might seem like the cause of spoilage, wicking moisture out of the ground is a major cause, as well, accounting for 50% or more of losses in outside storage. Storing bales on the ground can increase moisture in their outer portions by as much as 120%, according to Minimizing Losses in Hay Storage and Feeding authors.

If just 3 inches around the outside of a 5-foot round bale spoil, 19% of the dry matter will be lost, and the remainder of the bale’s nutritional value will decrease.

Proper storage, especially in areas with frequent rain, can help reduce hay losses by up to 50%. Store round and square bales off the ground (on a wood pallet, for example) and under cover, whether it’s a tarp or a roof.

Feeding hay inside

Use hay feeders or a haynet to help reduce waste in stalls. Researchers at Sam Houston State University, in Texas, compared the amount of hay wasted when feeding coastal hay on the ground versus from a hay feeder in stalls. The team found that horses wasted about 19.5% of hay fed on the ground versus 6% fed from a feeder (McMillian et al., 2010). Some owners, however, believe offering hay on the ground is a safer, more natural way to feed and helps reduce inhalation of particles such as dust or fungal spores.

Feeding hay outside

This can result in significant hay losses—upward of 60%.

When owners feed hay on the ground, horses often walk over or lie in it. This leads to contamination with dirt, mud, manure, and urine, all of which can result in feed refusal and losses. Then there are the weathering factors; physical dry matter losses are common, as is forage quality loss due to leaf shatter and leached nutrients such as carbohydrates and protein.

Krishona Martinson, PhD, professor and equine extension specialist at the University of Minnesota, in St. Paul, investigated feeders’ ability to reduce hay wastage in outdoor paddocks. She compared wastage when feeding from three commercially available small square bale feeders—a hayrack, a slat feeder, and a basket feeder — to that from feeding on the ground.

“All small square bale feeders we tested resulted in reduced hay waste compared to feeding hay off the ground in an out- door dirt paddock,” she says.

Martinson’s group also investigated the effects of nine round bale feeder types on hay waste. They found that each of the round-bale feeder designs created some waste, but all feeders wasted less hay than feeding on the ground.

Take-Home Message

Situations that call for sudden hay-type shifts include short hay supply and changes in horses’ nutritional needs due to age or health issues. Although having to make such a change isn’t ideal, blending old and new hay as much as possible and working with a veterinarian and equine nutritionist will help reduce your horse’s risk of colic and other potential digestive upset during this period.