Hay is a substitute for the grass and forage horses would eat if they were roaming freely. Different types of grass hay are available locally, depending on where you live. Good quality hay contains protein and vitamins, and it provides the fiber your horse needs for a healthy digestive system. The nutritional quality of hay is determined by protein and vitamin content. Another important quality issue is the cleanliness of the hay. Any hay can become contaminated with mold or dust if it is improperly cured or improperly stored. Moldy or dusty hay can cause serious, chronic respiratory diseases in horses. Whichever type of grass hay is available in your area, feed your horse only sweet smelling, clean hay.
The type of hay you feed also depends on the kind of horse you have. A young, growing horse or a lactating mare requires high nutrient profile hay, such as early bloom alfalfa. A recreational saddle horse has lower nutritional needs, and will do well on later cut hay. Horses must have the correct amount of fiber from hay to stay healthy, so lots of hay with the appropriate high, medium or low nutritional content should always be fed, supplemented with grain or mineral blocks as necessary.
Alfalfa and Clover
Alfalfa and clover are legumes, and not true grasses. Both alfalfa and clover are popular hays for horses in the Midwest, where they grow easily and offer multiple cuts per season. Alfalfa and clover provide high protein and calcium, as well as vitamins. Early bloom alfalfa hay offers the highest nutrient value. Succeeding cuts of clover and alfalfa have increasing fiber content with decreasing nutrient values. Clover stems have tiny hairs which can break off and create undesirable dust, especially in late cut hay or over-dried hay. Stored clover hay may develop a mold that makes horses slobber.
Early maturity timothy grass makes the most nutritious timothy hay, followed by middle maturity and then late maturity. Judge the maturity of the seedhead by rubbing it between your fingers. Early maturity will be the softest, and most of the seeds will remain on the stem when you rub them. Middle maturity seedheads will be more brittle, and some of the seeds will drop from the stem. Late maturity seedheads will crumble between your fingers. Timothy hay has fine stems and lots of leaves, making it a quality hay with easily digested fiber.
Fescue is a fine pasture grass, but it must be monitored carefully if cut for hay. Fescue grass hay contains mid-range nutrient values, which decrease as the fescue matures and the stem to leaf ratio increases. Late cut fescue hay provides low nutrition, but it provides high quality fiber. Fescue may contain a problematic endophytic fungus that interferes with the ability of a horse's blood to clot properly. Your extension office can test fescue hay for the fungus before you feed it to horses.
Bermuda grass grows in the southern US, where it is often used as a cash hay crop sold to other regions of the country. The nutritional content of Bermuda grass hay matches that of other grass hay, such as timothy.
Remember that the nutritional value of any hay is affected by weather and other growing conditions. A nutritional analysis should be done before you purchase hay for horses.
Safety With Grass Blends
Blends of field grasses that may include sorghum grass, Johnsongrass, Sudangrass or hybrids of these weedy types of grasses should not be fed to horses. These grasses can cause neurological damage to horses. Hay of this type may also contain unknown weeds, or poisonous weeds such as ragwort.
All hay should be examined for the presence of blister beetles or their body parts. These insects contain cantharidin, a toxin that causes severe digestive and urinary problems in horses.