Spring has sprung and green pasture is coming on like gangbusters in most parts of the country. For most of us, this is good news because green grass for horses relieves some pressure from searching for quality hay at a reasonable price. Of course, with the rising cost of fertilizer, it may be hard to decide which is the lesser of two evils: high-priced hay or high-priced fertilizer. However, if you have pasture and intend to utilize it for horses, there are some things to consider.

Keep in mind that going from dry hay and grain to lush, green pasture is a drastic change in diet and may increase the risk of founder or colic. Horses that are in the pasture full time, will gradually become accustomed to the emerging green grass as it comes up. But horses that haven’t had green grass should only be allowed to graze for an hour or two at first, then gradually increase grazing time by an hour every couple days until the horse is out full time. It is also a good idea for horses to have eaten dry hay prior to turnout so they are not overly hungry. Individual horses will have different tolerance levels to the diet change and the nutritional profile of the grass, so a slower introduction is usually better.

Spring pasture often looks beautiful and nutritious but can be very high in water and low in fiber content. In this stage of maturity, pasture may not meet a horse’s minimum requirement for dry matter intake and it may be necessary to provide 10–15 lbs. of dry hay per day until the pasture matures. Even when the pasture is sufficient to maintain horses in good body condition with no supplemental grain, there will still be nutrient deficiencies. Providing a forage balancer product such as Purina^® Enrich Plus™ will supply a balance of protein, vitamins and minerals to compliment pasture. This product is formulated to meet nutrient requirements of mature horses with 1–2 lbs. per day, whereas most feeds are formulated to be fed at a minimum of 3.5–4 lbs. per day.

Pasture simulates a natural environment for horses and is considered healthy from a nutritional standpoint and from a low-stress, mentally healthy perspective as well. You may have enough pasture to serve both functions but in many cases, available pasture is simply a place to run around and nibble for a few hours a day. You have to consider how many acres and the number of horses you have to determine if you have enough pasture to provide adequate grazing for the grass to play a significant role in your horses’ diet.

The very best pastures may support one horse per acre, but most conditions will require closer to 2–3 acres to sustain one horse grazing full time. The effective stocking rate will depend on the type of grass, fertilization and rain fall. For shorter varieties of grasses, such as Kentucky bluegrass, pasture must grow 3–4 inches tall to provide adequate forage for horses. Taller grasses, including Coastal bermudagrass, should sustain a height of 6–8 inches. Stocking rates may be improved if there is an option to rotate pastures.  Grazing tall forage varieties down to 3–4 inches and shorter varieties to 2 inches in height, then rotating to another pasture for four weeks can help maximize grazing potential of available acreage. Rotating pastures is also a good way to reduce the risk of internal parasite infestation. A good rule of thumb is that if you can see manure piles in your pasture and if horses are grazing close to those manure piles, your pasture is overgrazed and horses should be removed to let it recover.

Source: Karen E. Davison, Ph.D., Equine Nutritionist and Sales Support Manager, Purina Animal Nutrition