Alternative Grass Hays for HorsesBy Kentucky Equine Research Staff · November 4, 2003
Over the past several years, there has been increasing interest in cultivating alternative grasses to produce hays suitable for horses. The proceedings of the 2003 Equine Nutrition and Physiology Society symposium reports scientific research on three forages that may be of interest to horse producers: big bluestem, Indiangrass, and eastern gamagrass. None of these grasses appears in the extensive table of feedstuffs published in Nutrient Requirements of Horses, last printed in 1989 by the National Research Council, due in part, no doubt, to their relative novelty in horse management.
These warm-season grasses may prove valuable for future use in equine operations. Their chief advantage may be good productivity during the summer months when cool-season grasses such as orchard grass, tall fescue, and timothy are dormant.
Big bluestem (Andropogon gerardii) is a native perennial that grows in much of the continental United States, excluding Washington, Oregon, Idaho, California, and Nevada. The plant is most widely distributed in the Great Plainsand Midwest. This grass has tall, slender stems that are green throughout the growing season. As the plant develops to its mature height of three to six feet, however, the stem becomes coarser and bluish-purple, hence its common name. The seed heads usually have three spikelike projections that resemble birds' feet, giving rise to a popular alternate name for the plant, turkey foot.
Big bluestem grows best on well-drained soils and is adaptable to a wide variety of soil shortcomings including shallow depth, low pH, and low fertility. This perennial seems to be more drought-tolerant than other warm-season grasses. Livestock producers have used big bluestem for grazing and haymaking for several decades with satisfactory results. Cattle find the plant particularly palatable and will graze big bluestem to ground level.
Agronomists advise against the harvesting of big bluestem during the first year of growth, known as the establishment season. Haymaking should commence during the second growing season when the plants are approximately 20 inches tall. The type of horses being fed big bluestem hay will have a bearing on when it is cut. The most nutrient-dense hay is derived from plants in which the seed head has not yet emerged. Harvesting at this time also ensures optimal regrowth potential. Once seed heads emerge, hay quality drops but yields increase. Well-tended expanses of big bluestem can yield two to four tons of hay per acre.
Like big bluestem, Indiangrass (Sorghastrum nutans) is a perennial bunchgrass native to North
America. Although it grows predominantly on the tallgrass prairies of the United States, it can be found as far north as Manitoba, Canadaand as far south as Mexico. Other names for Indiangrass include wood grass, wild oat grass, and yellow Indiangrass.
Indiangrass usually grows in dense tufts with mature plant height varying from three to five feet. Taller plants are not unusual, with some reaching nearly ten feet. The six to 12-inch seed heads, also called spikelets, are yellow and have white hairlike structures protruding from them. Because they are glossy, almost to the point of iridescence, spikelets often appear gold and silver in sunlight.
Indiangrass thrives best on fertile bottom soils but also grows acceptably on sandy soils and dry slopes. Once seeded, Indiangrass spreads readily. This species provides high-yielding warm-season grazing and hay production.
Eastern gamagrass (Tripsacum dactyloides) is a third bunchgrass native to the United States. As a warm-season perennial, eastern gamagrass produces most of its growth from mid-April through mid- September, thus growing earlier than big bluestem and Indiangrass. Eastern gamagrass is well known for its height and can easily grow as tall as field corn. Fields of eastern gamagrass have been notoriously difficult to establish, but an extensive, specialized root system allows plants to flourish in an array of soils–compact, saturated, and dry. The plant competes poorly with weeds, so cultivators often take special measures to control unwanted vegetation.
Like the big bluestem, eastern gamagrass is best left untouched one year, and possibly two years, following seeding. Eastern gamagrass can be harvested as hay, with the first cutting usually occurring in mid-June when the grass is 24-36 inches tall. Harvests of regrowth can then be made every four to six weeks following the initial harvest. Six to eight inches of stubble should remain when cutting eastern gamagrass for hay. Yields of the forage have been as high as 10 tons of dry matter per acre, though yields of 3-6 tons are more typical. As with other forages, quality of hay made from eastern gamagrass depends primarily on plant maturity at harvesting. Young plants cropped prior to the boot stage will deliver more nutrition than more mature, fibrous plants.
Researchers at the University of Kentucky measured the voluntary intake of big bluestem, Indiangrass, eastern gamagrass, and timothy grass hays in a group of mature horses. While horses fed timothy grass hay had the highest voluntary dry matter intake, horses consumed the warm-season grass hays at intakes that met or exceeded those necessary to maintain body weight. Interestingly, nondetergent fiber (NDF) values for the hays corresponded to intake.
NDF values were 69.6, 74.1, 72.6, and 61.3 for big bluestem, eastern gamagrass, Indiangrass, and timothy grass hays, respectively. Timothy grass hay had the lowest NDF value and the highest intake. This relationship corresponds to the fact that palatability decreases with increasing NDF. Results of this study indicate that big bluestem, eastern gamagrass, and Indiangrass may be suitable components of an equine diet; however, further research should be performed on these warm-season grasses before they are added to rations as a matter of course.