Spring Turnout: Turning ranch horses out to spring pasture should take place gradually

As spring thaws winter’s chill and the landscape starts to turn green, it can be exciting – and a bit of a relief – to finally turn ranch horses out to pasture. 

However, experts remind horse owners extra time and care should be taken when returning horses to pasture to avoid laminitis, colic and/or diarrhea. 

A sensitive system

Horses are known for having a unique monogastric digestive system, in which plant matter is broken down via microbial fermentation in the hindgut. 

Microbes in the digestive tract vary depending on what the animal eats, and when the diet changes, so must the microbial population. 

Since these microbes are highly sensitive to changes in the diet and because sudden feed changes do not give the microbial population time to adjust, it is recommended to change a horse’s diet gradually over the course of a few weeks to avoid issues with colic and/or diarrhea. 

Additionally, Pennsylvania State University (Penn State) Equine Extension Educator Laura Kenny notes early spring growth tends to be high in non-structural carbohydrates (NSC), which includes sugars, fructans and starches that may cause problems in some horses. 

“These carbohydrates are an important energy source for horses, but they trigger laminitis for some horses with certain health conditions, such as laminitis, insulin dysregulation, Equine Metabolic Syndrome (EMS) and Cushing’s disease,” she explains in a Jan. 10 Penn State Extension publication. 

A gradual transition

Horses that have been kept in confinement during winter months are at highest risk of experiencing issues during spring turnout and should transition to pasture gradually. 

Multiple sources agree it is best to wait until pastures have six to eight inches of new growth before turning horses out to graze, even if it is for short periods of time. This allows plants time to recover and grow new leaf tissue. 

Once pastures are ready to graze, horses should be turned out for short periods of time – 15 to 30 minutes a day for the first few days – which can be slowly increased each day.

“In other words, allow horses to graze for 15 minutes on day one, 30 minutes on day two and 45 minutes on day three, on through day 20,” explains Dakota Farmer Senior Editor Curt Arens in a Feb. 26 article. “This gradual increase in grazing time each day allows the microbes in the gut of the horse to adjust to the change. By day 21, they should be able to graze with no time restrictions, unless there are other health concerns.” 

Experts also recommend turning horses out early in the morning when sugar levels in the grass are lowest and after feeding hay so they aren’t grazing on an empty stomach.

In situations where individuals can’t gradually reintroduce horses to pasture, Kenny suggests using grazing muzzles, which allow horses to drink water and take small bites of grass but prevents them from consuming large amounts of forage. 

She notes muzzles have been shown to reduce pasture intake by 30 to 80 percent, but multiple factors influence their effectiveness. 

“It can take some trial and error to find a style of grazing muzzle that works for your horse, but luckily there are many on the market,” she states. “When trying out grazing muzzles, realize it will take the horse some time to learn how to use it, especially if they have never had it on.” 

A less cautious approach 

On the other hand, horses that spent their winter out on big pastures instead of in confinement will require less caution on the producer’s end, as they can transition themselves to spring grass by grazing as it begins to grow.

Kenny notes very little grass will be available at first so horses won’t eat much, but as more grass comes in, their digestive tracts will naturally adjust to the new feed source. However, producers should continue to feed hay in to the spring to help with this transition.

“While this is less desirable from a plant biology and pasture health perspective, it means horses will be fine if they are turned out while pastures are greening up,” Kenny says. 

“An exception would be laminitis-prone horses with EMS or insulin dysregulation, as the NSC content of spring grass can become quite high and cause undesirable health issues,” she concludes. “It is always best to consult with a veterinarian when making pasture grazing decisions for laminitis-prone horses.” 

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.