Published July, 2009

Kentucky horse owners might find Bermudagrass to be a good summer pasture species for mares, foals, and yearlings, and it might also serve as an on-farm source of hay or bedding. These observations are based on a continuing four-year study at the University of Kentucky.

Cold-hardy bermudagrass cultivars, developed by plant breeder Charles Taliaferro at Oklahoma State University and marketed by Johnston Seed Company, can be established from seed, eliminating the costs and problems of establishment by sprigging (putting out small plants). "Wrangler" bermudagrass was marketed primarily as forage for cattle. "Reata," which is a blend of "Wrangler" and "Riveria" (a seeded turf-type bermudagrass), has been sold specifically for equine grazing.

Bermudagrass seed is very small (there are more than 2 million seeds per pound) and is coated with materials to facilitate seeding and germination. About one half of the coated seed weight is made up of these materials. Wrangler and Reata are sown at 6 pounds of coated seeds per acre. Coated seed costs about $300 per 50-pound bag.

An experimental bermudagrass pasture was developed at the University of Kentucky's Spindletop Farm in the spring of 2003. Coated seed was broadcast on a prepared seedbed and consolidated with a cultipacker.

Low temperatures in early summer in 2003 resulted in sparse bermudagrass stands, so we broadcast more bermudagrass seed in 2004. In 2005, the field was managed for establishment and mowed frequently because of severe infestations of spiny and red root pigweed. Cool-season grasses and winter annual weeds were controlled by glyphosate (Roundup) in spring every year when the bermudagrass is dormant. Broadleaf weeds were controlled with 2, 4-D dicamba in April or May each year.

Bermudagrass grows when air temperatures are above 65°F, and it grows exceptionally well up to 100°F, given timely spring and summer rains. Bermudagrass grows best when cool-season grasses are stifled by high temperatures in July and August. Growth slows in October as nights cool, stops growing at 50°F, then loses its green color as leaf cells die ("brown off") after the first frosts in mid-October. There has been no "winter kill" in Spindletop's Wrangler bermudagrass pasture in any of the past six winters, indicating that these plants are really cold-hardy in Kentucky.

The field was grazed by mature horses in the summers of 2006 through 2008 and again starting in June 2009. Grazing of bermudagrass at Spindletop usually starts about the first of June, depending on growth during the spring weather. In the three years of grazing this pasture with mature horses, horses feeding on the bermudagrass have not been supplemented with hay or other feeds, nor has the pasture been irrigated. The horses maintained body weight and body condition scores without supplements and irrigation, even in occasional droughts. Surplus herbage was clipped in June, July, and August.

Stockpiled herbage (surplus herbage) provided some reservoir of energy when grass growth was limited by rainfall in September and October or by low temperatures.

Extending Your Grass

With Kentucky bermudagrass you can expect 120 to 140 days of grazing each season. The season can be extended by grazing of the senescent (browned off) herbage. Research in Arkansas indicates that standing browned off herbage retains its nutrients for some time. The grazing season can also be extended by over-seeding the stand of bermudagrass with annual ryegrass or other cool-season forages, although UK researchers have not looked at that option.

In Kentucky, bermudagrass might yield up to 8 tons of dry matter per acre each 140-day growing season. This means that bermudagrass growth rates could average 150 pounds per acre per day for 120 days, which could support six mares per acre consuming 25 pounds per day. To support these high pasture growth rates, UK researchers applied 50 pounds of nitrogen as urea every four weeks or up to 200 pounds of nitrogen per acre over the growing season. The pastures also received broadcast potassium, as chloride, at 200 pounds per acre based on soil testing.

A simple rotational grazing system was used from 2006-2009. The field perimeter was secured with four plank fences and electrified high-tensile fences. Four, five, or six temporary paddocks were created with three strands of polytape on insulated steel T-posts. The first three years portable waterers drawing from city water were moved around in the temporary paddocks. In 2009 paddocks were arranged around a single insulated Mirafont waterer to facilitate watering the horses.

The 4.8-acre field in 2006 was divided into six 0.8-acre paddocks. That year the field was stocked with 11 adult Thoroughbred and Quarter Horse mares (body weight averaged 1,112 pounds) at 2.3 mares per acre overall. When confined to a 0.8 acre paddocks, the stocking density was 13.75 mares per acre.

Horses were moved from paddock to paddock every five to seven days according to the forage supply and herbage quality. After the horses were removed, grazed pastures were mowed to 4 inches and fecal material was broken up and spread with a spring tine harrow. Pastures were grazed again after 21-28 days of growth in the absence of horses.

Horses grazed bermudagrass according to foraging theory: they grazed patches of bermudagrass where they could ingest herbage fastest with the least effort. Mares first grazed the hummocks that formed over old urine patches where the herbage was tallest, least mature, leafiest, greenest, and had the highest nutritive value.

Bermudagrass herbage has few macro- or micronutrient limitations for adult mares and geldings, and these classes of horses might not need supplements when on bermudagrass pastures. The soluble carbohydrates and protein of bermudagrass herbage are low and unlikely to cause nutritional problems in horses. There are no alkaloids or other harmful mycotoxins normally present in bermudagrass in Kentucky.

Prepared by Bob Coleman, PhD, PAS, UK Department of Animal and Food Sciences, Glen Aiken, PhD, USDA Agricultural Research Service, and Charles Dougherty, PhD, UK Department of Plant and Soil Sciences, for the 2009 UK Equine Field Day, June 27, 2009.