Alfalfa (Medicago sativa), a flowering perennial legume, is one of the most widely cultivated forage crops globally. It is recognized for its unique ability to fix nitrogen in the soil, which benefits subsequent crops. Its deep, extensive root system allows it to withstand drought and access nutrients from deeper soil layers than most grasses. This resilience has secured alfalfa’s importance in agricultural systems worldwide.
Alfalfa as a Staple Crop for Domestic Animals
Alfalfa is a highly prized feed source for domesticated animals, supporting high production demands. Dairy cows are among the primary consumers, utilizing high-quality alfalfa hay or silage in their rations to sustain milk output. The forage is valued for its nutrient density and palatability, which encourages greater feed intake.
Small ruminants, such as sheep and goats, also consume alfalfa, often in the form of hay or pellets. For young, growing, or lactating animals, the dense nutrient profile provides the necessary building blocks for development and production. Beef cattle operations utilize alfalfa as well, frequently feeding lower-quality or mixed hay to mature, non-lactating animals to provide protein and fiber supplementation.
Non-ruminant livestock, notably horses, are fed alfalfa, typically as cubed or baled hay. Its high calorie-to-volume ratio makes it suitable feed for working horses, growing foals, and lactating mares with higher energy requirements. Small companion animals like rabbits are often given alfalfa pellets when young, ensuring adequate protein and calcium intake for rapid growth. The feed’s versatility—as hay, silage, cubes, or pellets—allows producers to tailor the physical form to the specific species and management system.
Wildlife Consumers and Foragers
The high palatability of alfalfa attracts various non-domesticated species, which view cultivated fields as an opportunistic food source. Large wild herbivores, including deer and elk, readily graze on alfalfa fields or consume stored hay. Consumption by wild ruminants, especially during winter, can be detrimental because their specialized gut microbes are adapted to digesting woody browse, not rich legume hay.
Several small mammals interact with alfalfa, often acting as agricultural pests. Burrowing animals like gophers and voles consume the plant’s roots and crowns, causing significant stand damage and mortality. Groundhogs, known for their above-ground feeding, will also include alfalfa in their diet, further contributing to crop loss.
Insect pests specifically target the plant, with the alfalfa weevil being a major concern. The weevil larvae skeletonize the leaves, causing severe defoliation and reducing the yield and quality of the hay crop. Various aphids, such as the pea and spotted alfalfa aphid, are fluid feeders that extract sap and can inject toxins. This results in plant stunting and yellowing, particularly in young alfalfa stands.
Nutritional Profile and Digestibility
Alfalfa is preferred due to its superior nutritional composition compared to most grass forages. High-quality alfalfa hay typically contains a crude protein concentration ranging from 16% to over 21% on a dry matter basis. This high protein content is a primary reason for its inclusion in the diets of high-producing livestock.
The fiber content is analyzed using two key metrics: Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF). High-quality alfalfa has lower NDF (often below 40%) and ADF (often below 32%) concentrations than grass hay, which indicates a higher potential for feed intake and rapid digestibility. The faster breakdown of its cell wall material in the rumen contributes significantly to its high digestible energy value.
Alfalfa is also notably rich in minerals, particularly calcium, with concentrations often exceeding 1.2% of the dry matter. This high calcium level is beneficial for lactating animals, as they require significant amounts of the mineral for milk production. The combination of highly digestible fiber and high nutrient density makes alfalfa an efficient and concentrated source of energy for many animal species.
Consumption Safety and Contraindications
Despite its nutritional benefits, feeding alfalfa requires careful management due to safety considerations. In ruminants like cattle and sheep, the rapid fermentation of soluble proteins in fresh alfalfa can lead to frothy bloat. This occurs when a stable foam forms in the rumen, trapping fermentation gases and preventing their expulsion, which creates a life-threatening pressure buildup.
The high calcium content is a concern for specific non-ruminants, particularly mature horses. Diets overly reliant on alfalfa can predispose horses to the formation of calcium carbonate urinary stones (urolithiasis) or intestinal stones (enteroliths). The excess protein is also converted to urea, causing increased water consumption and urination, which can be problematic for horses with pre-existing kidney conditions.
Another risk is the potential for mold growth and spoilage during hay storage. Moldy hay may contain mycotoxins, toxic compounds produced by fungi, capable of causing health issues like liver damage or impaired immune function. Horses are particularly susceptible to the respiratory hazards of mold spores, which can lead to recurrent airway obstruction.