Forage is any edible part of a plant, other than separated grain, that feeds grazing animals or can be harvested for feeding. That includes the leaves, stems, and sometimes roots of grasses, legumes, and broadleaf plants. Forage is the foundation of livestock nutrition worldwide, covering roughly 3.2 billion hectares of the earth’s surface as permanent meadows and pastures, about two-thirds of all agricultural land on the planet.
The Three Main Types of Forage
Forage plants fall into three broad categories: grasses, legumes, and forbs. Each plays a different role in pastures and hay fields.
Grasses belong to the plant family Poaceae and make up the bulk of most pastures. Common forage grasses include timothy, orchardgrass, and smooth bromegrass. Timothy is the most widely planted forage grass in the northeastern United States and pairs well with legumes in mixed fields. Orchardgrass matures earlier in the season and grows more aggressively than timothy or bromegrass, making it a popular choice where faster establishment matters.
Legumes belong to the family Fabaceae and have a special advantage: they pull nitrogen from the air and fix it in the soil, reducing the need for fertilizer. Alfalfa is the most widely grown forage legume in the world and the highest-yielding perennial forage crop in many countries. Red clover, a shorter-lived perennial, and birdsfoot trefoil, which doesn’t cause bloat in cattle the way some legumes can, are also common choices.
Forbs are any herbaceous broadleaf plants that aren’t grasses or grass-like. In a pasture, forbs can be beneficial wildflowers and herbs, or they can be weeds. Some forbs are highly nutritious, while others are toxic to livestock.
Forage vs. Fodder
The two terms overlap but aren’t identical. Forage refers specifically to plant material that animals graze on or that’s harvested from fields. Fodder is a broader term meaning any food fed to livestock, which can include grain, sprouted barley, or processed feed mixes. In current usage, “fodder” often refers to sprouted grain systems, while “forage” points to pasture-based and hay-based feeding.
How Forage Quality Is Measured
The nutritional value of forage comes down largely to fiber content. Two measurements matter most: the total plant fiber (which determines how much an animal can eat in a day) and the less-digestible portion of that fiber (which determines how much energy the animal actually gets from it).
For legumes like alfalfa, total fiber below 40% of the dry matter is considered good quality, while above 50% is poor. Grass forages have naturally higher fiber, so the thresholds shift: below 50% is high quality, above 60% is low. For the less-digestible fiber fraction, the goal for both grasses and legumes is to stay below 35%. These numbers change with maturity. The longer a plant grows before cutting, the more fiber builds up and the less digestible it becomes.
Preservation: Hay, Haylage, and Silage
Freshly cut forage contains 75 to 80% moisture, which is far too wet to store without spoiling. How you dry it determines what you end up with.
Dry hay needs to reach 14 to 18% moisture before baling, with larger bales requiring the lower end of that range. At these levels, mold and bacterial growth essentially stop, and the hay can be stored for months. Haylage is a middle ground, dried to 60 to 65% moisture and then sealed in plastic wrap or a bunker where it ferments. Silage follows the same fermentation principle but is typically made from corn or other crops chopped while still quite wet. The fermentation process preserves nutrients through natural acids, similar to how sauerkraut is preserved.
How Much Forage Livestock Need
Forage requirements vary by species, but the general principle is the same: grazing animals need a large volume of plant material relative to their body size. Horses, for example, should receive at least 2% of their body weight in forage per day to keep their digestive systems functioning properly. For a 1,000-pound horse, that’s a minimum of 20 pounds of hay or pasture daily. Cattle have similar requirements, and for dairy cows, forage quality directly affects milk production.
Grazing Management and Regrowth
Simply turning animals loose in a field year-round degrades pastures over time. Rotational grazing, where livestock are moved between paddocks on a schedule, gives plants time to recover. Research on grazing systems has tested recovery intervals ranging from 8 to 40 days, with grazing periods of 2 to 16 days per paddock. The right balance depends on the species of grass, the season, and how closely the animals graze.
Smooth bromegrass, for instance, needs roughly five weeks of recovery before its regrowth shoots are ready to support another round of grazing. Grazing too soon, especially close to the ground, damages the crown tissue where new growth originates. The practical rule is to move animals before they graze plants down to the base and to wait until regrowth is well established before bringing them back.
Environmental Role of Perennial Forages
Perennial forage systems do more than feed animals. Their deep, permanent root systems hold soil in place, filter water, and store carbon underground. Research comparing perennial forages to annual crops found that perennial systems increased soil carbon stocks by up to 0.9 metric tons per hectare per year. Some tropical grasses reached total soil carbon levels of 94 metric tons per hectare in the top meter of soil. Annual forage crops like pearl millet, by contrast, actually lost carbon at a rate of 0.25 metric tons per hectare per year.
This matters because soil carbon improves soil structure, water-holding capacity, and fertility while also removing carbon dioxide from the atmosphere. Perennial forages provide continuous biomass input to the soil throughout the year, making them more efficient at storing carbon than either legume-only systems or annual forages.
Toxic Plants in Pastures
Not everything growing in a pasture is safe. Dozens of common weeds are toxic to cattle, sheep, and horses. Some of the most dangerous include poison hemlock, water hemlock, larkspur, lupine, locoweed, and death camas. Others like bracken fern, chokecherry, and tansy ragwort cause problems ranging from liver damage to sudden death depending on the amount consumed.
These plants can also end up in hay if they’re growing in a field at harvest time. Animals that might avoid a bitter plant while grazing sometimes eat it unknowingly when it’s dried and mixed into a bale. Regular pasture inspection and weed management are the most effective ways to reduce the risk, particularly in newly established fields or areas recovering from drought where desirable forages are thin and weeds have room to establish.