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How Many Horses Per Pasture?By Kentucky Equine Research Staff · September 25, 2014

Turning horses out to graze has many advantages for both the equines and their owners. Pastured horses can nibble small amounts of forage steadily, following a natural eating pattern. They get social contact as they interact with their peers, and tend to develop fewer stereotypies than stalled horses.

Free-choice exercise in a large area is essential in helping young horses develop a strong skeleton, and also minimizes stiffness in arthritic older horses. Horse owners benefit because they can spend less time cleaning stalls and less money for hay compared to expenses involved in keeping horses stalled. Horse pastures also self-fertilize to some extent, though best management may still require the application of commercial fertilizers.

All these advantages can be negated by overstocking and overgrazing. Putting too many horses in too small a space can damage plants, soil, and ground water quality. Horses are selective grazers, favoring some forages and ignoring other plants. Without sufficient acreage, this grazing pattern will result in areas where the soil has been bared and other rough patches of undesirable weeds. Bare soil is easily compacted by horses’ hooves, allowing it to hold less moisture and discouraging regrowth of grasses and legumes. Bare soil is easily eroded, leading to a loss of fertile topsoil as the dirt washes into streams and ponds.

Overstocking can also put horses at a higher risk for encountering parasite larvae in the pasture. Normally, horses with plenty of open space will graze in some areas and defecate in others. They tend not to graze near manure piles and thus avoid ingesting the parasite larvae found in and close to manure. When pastures are overstocked, horses are forced to graze closer to these contaminated areas.

Stocking rate varies by region. In areas with excellent forage growth, each horse requires a minimum of an acre or two, while in dry or poorly vegetated regions, a much larger grazing area must be provided for each horse. Walking several lines across a pasture can give property owners some idea of soil condition and forage cover in relation to bare spots. Unless the overgrazing has been extreme, damaged fields will often recover if horses are removed for a while and the forage is allowed to grow. Badly overgrazed areas may have suffered permanent loss of desirable forage plants, a heavy weed cover, and considerable soil erosion. Reducing herd size on a particular field, rotating horses among several fields, and supplementing grazing with hay are ways of managing pastures to minimize overgrazing.