Heading into winter, when is the right time to take horses off pasture, or can horses be kept on pasture throughout the winter months?
Proponents of winter grazing cite wild horses that remain on pasture during the winter and question why the same can’t be done for domesticated horses.
In a University of Minnesota (UMN) extension Horse Newsletter, Krishona Martinson, a UMN extension equine specialist, explains how to properly house horses over the winter and why owners should avoid leaving them on pasture.
After a killing frost, pasture forages stop growing, even if they still look green. Because growth has stopped, it is much easier for pastures to become overgrazed. It is recommended that pasture forages have 3 inches of regrowth when going into the winter months to give some protection to the plants from the harsh conditions.
“After waiting seven days following the first killing frost, horses can resume grazing until the pasture forages are, on average, grazed down to 3 inches,” Martinson explains. She notes the time to reach this level of regrowth depends on stocking rate, weather conditions, productivity of the pasture, and general pasture management.
Once pastures are grazed down in the fall, transition horses to hay and house them in a dry lot, keeping them off pastures until the next year when forage regrowth reaches 6 to 8 inches. This practice is similar to rotational grazing during the growing season; however, in the fall, forage growth has stopped.
Martinson notes that while wild horses are able to graze throughout the winter months, there are major differences between them and domesticated horses. Wild horses graze on poor, sparse pastures and travel miles in a day to obtain the proper number of calories and nutrients. The wild pastures are often overgrazed, and the horses typically lose a large amount of their body weight over the season.
Domesticated horses, on the other hand, graze on small, well-maintained pastures, have higher stocking rates, need higher quality diets, and can’t lose large amounts of body weight.
Martinson notes that a study done in Colorado found that pasture grasses under snow had high variability in nutrients and were higher in nonstructural carbohydrates. This is dangerous to horses with laminitis and other metabolic diseases and shows why these forages shouldn’t be relied on over the winter months.
Overall, Martinson recommends horses be kept on dry lots over the winter and fed hay. This prevents overgrazing, pasture weed infestations, and improves regrowth in the spring along with subsequent summer production.
“Bottom line: If you have a dry lot, use it over the winter months,” Martinson says. “If horses have access to pastures over winter months, owners should expect a less productive pasture, especially if they have high stocking rates,” she concludes.