Horses need high quality, digestible forage. Unlike cattle or sheep, ruminant animals having a four compartment stomach, horses have a simple stomach, meaning only one stomach. Ruminants are capable of utilizing high fibre feeds to a greater extent than horses.
Thus, the importance of not allowing forages to reach advanced stages of maturity in horse grazed pastures. The nutritional composition of pasture forages must be determined if it will be the major feed source.
The options on pasture management are then determined. Pasture management or improvements may include establishment, renovation or merely maintenance through proper grazing management.
Pasture Use:
The first decision on pasture use is to determine if sufficient acreage is available to maintain a nutrition program. Horses benefit from exercise and often prefer being outside.
This need can be met on a relatively small, well-drained lot. But if the pasture is to provide a major feed source, other factors must be considered, including nutritional value of the pasture forages and pasture carrying capacity.
Nutritional Value:
Native pastures in North Dakota provide ample nutritional quality throughout most of the grazing season. Horses can be maintained on native pastures if water is abundant and trace mineralized salt plus phosphorous are supplemented. Typically, native pasture forages are high in nutritional value when actively growing and become lower in nutritional value with maturity.
Supplementing with high quality feed may be desired from mid-August on if plants are allowed to mature and regrowth is limited. Cool-season grasses such as Kentucky bluegrass, smooth bromegrass, green needlegrass, and western wheatgrass will obtain a second cycle of growth in September and October, allowing for high quality feed during this later time period. However, during times of limited fall precipitation or drought conditions, this regrowth pattern may not occur or be reduced and supplementation may be required.
Established domestic grass pastures (smooth bromegrass, Kentucky bluegrass, intermediate wheatgrass) can meet most horses’ nutritional needs throughout much of the grazing season. Typically, these grasses may drop below the required nutritional needs of mature horses and will drop below the needs of lactating mares in mid-summer.
Carefully monitor the grass and the body condition of the animals and supplement with quality feed when plants become rank or grazed too close. Once sufficient regrowth has occurred (approximately 4 to 6 inches or the three- to four-leaf stage), horses can be returned to that pasture.
Adding a legume with the grass mixture when establishing a permanent horse pasture will help maintain the animals’ nutritional needs through the summer period when nutritional quality of domestic grasses is low. Bloat (flatulent colic) may occur in horses not slowly adapted to pastures with a high percentage of legumes. Legumes such as alfalfa or clovers can be included in a pasture mix, but sweetclover is not recommended for pregnant and milking mares. Legumes such as alfalfa mature later and provide a high quality feed in the summer.
Carrying Capacity:
Carrying capacities will vary throughout North Dakota due to precipitation difference, range sites (soil type), topography, salt or alkaline conditions, and degree of grazing management.
These differences will affect both native pastures and established domestic grass and grass-legume pastures. Domestic grass and grass-legume pastures will produce more forage than native pastures, allowing for a higher stocking rate.
Typically, 10 to 18 acres of well-managed native pasture is required in western North Dakota, and 3 to 6 acres in eastern North Dakota to maintain one mature horse for a six month grazing season. Carrying capacity of domestic grass pasture will vary dramatically from region to region within the same plant species, as well as among different plant species.
For instance, Kentucky bluegrass produces about one-half and crested wheatgrass three-fourths the forage as smooth bromegrass. Kentucky bluegrass and smooth bromegrass do not tolerate low moisture conditions as well as intermediate and crested wheatgrass, thus minimizing their use in western North Dakota.
Crested wheatgrass becomes rank much earlier than the other tame grasses, providing only limited use during the grazing season. If alfalfa is incorporated into the seed mixture, forage production may increase 50 to 100 percent.
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