Hay is forage—leafy plants that have been cut, dried, and baled for use as animal feed when fresh pasture is unavailable. The nutritional content and physical characteristics of hay vary widely, making selection important for animal health. Hay types are fundamentally categorized into two major botanical groups: grasses and legumes. This classification dictates the forage’s basic nutritional profile and suitability for different livestock and pets.
The Fundamental Difference: Grasses Versus Legumes
The most basic distinction in hay types lies in their plant family of origin: grasses or legumes. Grass hays, which are monocots, generally possess a higher fiber content and a lower concentration of crude protein and minerals. These characteristics make them the preferred forage for animals requiring a low-calorie, high-fiber diet for digestive health.
Legume hays belong to the family Fabaceae (the pea family) and are dicots. Legumes form a symbiotic relationship with bacteria in their root nodules, enabling nitrogen fixation. This process results in a significantly higher protein and mineral content in the plant tissue, providing a denser nutrient package than grass hays.
Common Grass Hay Varieties and Their Suitability
Grass hays are the most common forage, valued for their high fiber content and balanced nutritional profile suitable for maintenance diets. Timothy hay is a popular variety, recognized by its long, hollow stems and cattail-like seed heads. It is an excellent option for most horses and is regarded as the standard for many small herbivores, such as rabbits and guinea pigs, due to its balance of high fiber and low protein and calcium.
Orchardgrass, a cool-season perennial, is known for its palatability and soft, leafy texture. It offers moderate levels of protein and energy, making it a versatile choice for horses and other livestock. Its soft nature can also benefit animals with respiratory issues or those that are picky eaters.
Fescue hay is a durable forage often used for cattle due to its moderate fiber and protein content. A consideration with fescue is the potential presence of an endophyte fungus, which can produce toxins harmful to livestock, particularly pregnant mares. Producers often choose endophyte-free or novel endophyte varieties to mitigate this health risk.
Brome hay, such as smooth bromegrass, is a soft, leafy, and palatable cool-season grass. It provides good digestibility and moderate energy, making it a desirable choice for horses, including those in maintenance or light work. Its soft texture and high leaf-to-stem ratio also make it suitable for older horses who may have dental issues.
Legume Hays: High-Protein Forage Sources
Legume hays are suitable for animals with elevated nutritional demands due to their high concentration of protein, energy, and calcium. Alfalfa, also called lucerne, is the most well-known legume hay, offering a crude protein content ranging from 15% to 20%. This dense nutritional profile makes it a valued feed for high-producing dairy cows, growing animals, and pregnant or lactating animals.
The high calcium level in alfalfa, often exceeding 1.2%, is beneficial for bone development in young stock. However, this rich nutrient concentration means alfalfa is typically not fed free-choice to mature, sedentary animals. Feeding it exclusively can lead to excessive weight gain or an unbalanced calcium-to-phosphorus ratio, so it is often mixed with grass hay to moderate nutrient intake.
Clover hay, including red and white varieties, is a common legume forage providing protein typically between 16% and 20%. Red clover hay is valued for its high digestibility and nutrient content, supporting milk production in dairy cattle and growth in young stock. Clover can be more challenging to cure and bale than grass hay due to its higher moisture content, requiring careful handling to prevent mold.