What Animals Eat Alfalfa? From Livestock to Wildlife

Alfalfa ranks among the most widely consumed forage crops on Earth, and the list of animals that eat it stretches far beyond the dairy barn. Cattle and horses are the headline consumers, but poultry, farmed fish, wild deer, rabbits, pocket gophers, and a host of insects all feed on alfalfa in one form or another. The plant’s unusually high protein and calcium content makes it attractive to a range of species, though it also carries some less obvious risks depending on who is eating it and how.

Why So Many Animals Want It

Alfalfa’s appeal comes down to its nutritional density compared with other common forages. Analyses of alfalfa hay and haylage show crude protein levels in the range of roughly 127 to 142 grams per kilogram of dry matter, which is substantially higher than typical meadow hay at around 79 to 88 grams per kilogram. Calcium levels follow the same pattern, with alfalfa delivering more than double the calcium found in standard grass hay.¹ That protein and mineral punch is what draws livestock producers and, unintentionally, wildlife toward alfalfa fields. One trade-off worth knowing: fiber in alfalfa tends to be less digestible than fiber in grass hays. Older research comparing alfalfa with brome grass and reed canary grass found that fiber digestion coefficients were considerably higher for the grasses.² So alfalfa is not the best choice when maximum fiber digestion is the goal, but its protein advantage usually wins out in ration planning.

Dairy and Beef Cattle

Cattle are far and away the largest consumers of alfalfa worldwide. Dairy operations rely on it heavily because higher protein intake translates directly into milk components. One study comparing dairy cows fed diets that included alfalfa silage alongside alfalfa hay found that milk yield, milk protein, and milk fat all increased compared with a control diet, with fat-corrected milk production significantly higher in the alfalfa silage group.³ Removing alfalfa from the ration tells a similar story in reverse: when cows were fed diets that replaced alfalfa hay and corn silage with an oat-vetch mixed silage, milk protein yield dropped by about 22% and fat yield dropped by roughly 16%.⁴ The economic incentive to keep alfalfa in the diet is strong.

Beef cattle also benefit, though the economics look different because weight gain rather than milk is the target. Most beef operations use alfalfa hay as a supplement to grass pasture rather than as the sole forage, partly to control costs and partly because of the bloat risk discussed below. In feedlot settings, alfalfa hay helps maintain rumen health by providing effective fiber alongside high-energy grain rations. Research on particle size has shown that how finely you chop the hay does not significantly change total intake, fiber digestibility, or milk yield in dairy cattle, which gives producers some flexibility in how they process it.⁵

The Bloat Problem in Cattle

Fresh alfalfa pasture poses a serious and sometimes fatal risk to cattle: frothy bloat. When cattle graze lush, immature alfalfa, soluble proteins in the plant (particularly a fraction known as Fraction 1 protein) create a stable foam in the rumen that traps gas. The animal cannot belch it away, pressure builds, and the rumen distends dangerously. Bloat is positively associated with the level of soluble protein in alfalfa, and the risk drops as the plant matures because those protein levels decline.⁶

The problem is common enough that researchers have tested a range of prevention strategies. In one crossover experiment, eleven out of twelve steers developed clinical bloat on pure alfalfa pasture. Treating the pasture with a pluronic detergent called ALFASURE prevented bloat in all twelve animals. Mixing sainfoin, a tannin-rich legume, into the alfalfa pasture prevented bloat in about half the steers.⁷ Another approach involves feed additives like monensin, which reduced bloat severity by up to about 73% at higher doses, likely by reducing protozoal numbers in the rumen and thereby cutting gas production.⁸ The poloxalene-based product Bloat Guard was the only additive tested in one study that completely prevented bloat.⁶

This is mostly a pasture issue, not a hay issue. Dried alfalfa hay rarely causes bloat because the drying process denatures the soluble proteins responsible for foam formation. The practical takeaway for ranchers: alfalfa hay in the feed bunk is straightforward, but turning cattle out on a pure stand of vegetative alfalfa requires bloat prevention measures.

Horses

Horses are the other major domestic consumer of alfalfa, and the relationship is complicated. On the positive side, alfalfa’s high protein and calcium content makes it useful for growing horses, lactating mares, and hard-working performance horses that need calorie-dense forage. There is also evidence that alfalfa’s buffering capacity may protect against gastric ulcers. Horses fed high-protein, high-calcium diets have been found to have fewer and less severe gastric ulcers.⁹

The downside is that alfalfa is a well-established risk factor for enterolithiasis, which is the formation of mineral stones in the large intestine. The same high mineral content that buffers stomach acid can contribute to stone formation in the colon, especially in certain geographic regions where water mineral content adds to the load. Enteroliths can cause life-threatening intestinal obstructions that require emergency surgery.⁹ Many equine veterinarians in the western United States recommend limiting alfalfa in the diet of horses prone to enteroliths, or at least mixing it with grass hay to reduce overall mineral intake.

A separate hazard for horses eating alfalfa hay is blister beetle contamination. Cantharidin, the toxin produced by blister beetles, is extremely potent. Horses that ingest alfalfa hay contaminated with crushed beetles can develop severe toxicosis, with damage to the gastrointestinal tract, urinary system, and heart.¹⁰ This is primarily a concern with alfalfa hay harvested in the southern United States during summer months, when beetle populations peak. Horse owners in those regions learn to inspect hay carefully and buy from producers who use harvesting practices designed to minimize beetle contamination, such as avoiding crimper-conditioners that crush beetles into the hay.

Poultry

Chickens and other poultry eat alfalfa in a different form than ruminants. Dehydrated alfalfa meal has been used in layer rations for decades, primarily because the carotenoid pigments in alfalfa produce deep golden-orange egg yolks that consumers prefer. Early research established that egg yolk pigmentation can be effectively increased by raising the dietary level of dehydrated alfalfa meal.¹¹

More recent work has looked at low-fiber alfalfa meal as a partial protein replacement for soybean meal in layer diets. Results showed that egg production was not reduced, and yolk quality actually improved: yolk color was significantly enhanced, and yolk cholesterol decreased while beta-carotene content increased.¹² For backyard chicken keepers, tossing fresh alfalfa or alfalfa sprouts into the run is a simple way to boost yolk color naturally. Commercially, alfalfa meal remains a common additive in organic and pasture-raised layer feeds where synthetic pigments are not allowed.

Fish in Aquaculture

Alfalfa shows up in an unexpected place: fish feed. As aquaculture grows and fishmeal prices climb, researchers have been testing plant-based protein alternatives for farmed fish. Alfalfa leaf protein concentrate has been studied as a partial fishmeal replacement in diets for tilapia. Cytoplasmic leaf protein from alfalfa actually produced growth rates higher than a standard fishmeal diet when it replaced up to about 35% of the fishmeal protein. No mortality was observed during the nine-week trial at any inclusion level, though higher concentrations depressed growth.¹³

Rainbow trout, a cold-water species with different nutritional demands, have also been tested with alfalfa nutrient concentrate at inclusion levels ranging from 5% to 20% of the diet as a fishmeal replacement.¹⁴ The aquaculture industry is still scaling these approaches, but alfalfa’s high protein content and year-round availability make it a promising ingredient as the sector moves toward more sustainable feed formulations.

Sheep, Goats, and Other Small Ruminants

Sheep and goats eat alfalfa readily and benefit from the same high protein and calcium content that makes it valuable for cattle. Lactating ewes and does, in particular, thrive on alfalfa-heavy diets because their protein demands are steep during milk production. Like cattle, sheep on fresh alfalfa pasture can develop bloat, though the risk is somewhat lower because sheep tend to graze more selectively and consume less of the frothy, immature foliage at once.

Alfalfa also contains phytoestrogens, plant compounds that mimic estrogen. These compounds, which include isoflavones like daidzein and genistein as well as coumestans, can affect reproductive function in grazing livestock when present at high enough concentrations. The effects are species-specific and depend heavily on exposure duration, the age and health of the animal, and the stress conditions the plant itself has experienced. At elevated concentrations, phytoestrogens have been shown to impair fertility in both cattle and sheep.¹⁵ On the other hand, some of these same compounds have potential benefits. Research has identified that certain isoflavones stimulate immune cell production and can promote protein synthesis, increase the lean-meat ratio, and boost weight gain in cattle and sheep.¹⁵ Whether phytoestrogens are a net positive or negative depends on the dose and the management context. Producers who rely heavily on alfalfa during breeding season typically monitor their animals for signs of irregular estrous cycles.

Wildlife That Raid Alfalfa Fields

Alfalfa fields are magnets for wild herbivores. White-tailed deer, mule deer, elk, and pronghorn all forage on alfalfa when given the opportunity. The combination of high protein and palatability draws them in, especially during late summer when native forage dries out and loses nutritional value. In many western states, wildlife damage to alfalfa fields is a persistent source of conflict between ranchers and game management agencies. Elk in particular can consume substantial tonnage from irrigated alfalfa fields near mountain habitat.

Wild rabbits, both cottontails and jackrabbits, graze alfalfa heavily and can significantly reduce yields in young stands. Underground, pocket gophers feed on alfalfa roots and crowns, killing plants outright and creating mounds that damage mowing equipment. The combination of above-ground and below-ground herbivory from wildlife can noticeably reduce forage production, particularly in fields adjacent to undisturbed habitat.

Smaller mammals including ground squirrels and prairie dogs also feed on alfalfa where their ranges overlap with cultivated fields. Even waterfowl sometimes graze on young alfalfa growth in irrigated areas. For wildlife managers, alfalfa food plots are a deliberate tool to attract and sustain game populations, which underscores just how universally appealing the plant is as a food source.

Insects That Feed on Alfalfa

The alfalfa weevil is the most economically damaging insect herbivore of the crop. Both adults and larvae feed on alfalfa, damaging terminals, foliage, and new crown shoots, but the larvae cause the bulk of the damage. Heavy feeding can result in significant loss of biomass, especially leaf tissue, and can slow plant growth and delay crop maturity. Beyond volume losses, the feeding reduces forage quality by lowering crude protein content in the remaining leaves.¹⁶ In severe infestations, entire first cuttings can be rendered nearly worthless.

Other insect pests include aphids (pea aphids and blue alfalfa aphids), various caterpillar species, and leafhoppers, all of which feed on alfalfa to varying degrees. On the beneficial side, alfalfa flowers provide nectar and pollen for honeybees, bumblebees, and leaf-cutter bees. Alfalfa seed production depends heavily on pollination by leaf-cutter bees, which are commercially managed for exactly that purpose. The same crop that feeds livestock and wildlife also plays a role in supporting pollinator populations, making alfalfa fields ecologically busier places than they might appear from the road.

Rabbits, Guinea Pigs, and Small Herbivore Pets

For pet owners, alfalfa is a familiar name on feed bags. Young rabbits under about one year of age are typically fed alfalfa hay because they need the extra protein and calcium for growth. Adult rabbits, however, are usually switched to grass hay like timothy because the high calcium in alfalfa can contribute to urinary sludge and bladder stones over time. The same logic applies to guinea pigs: young and pregnant animals benefit from alfalfa hay, while healthy adults do better on lower-calcium alternatives.

Chinchillas, degus, and even some species of tortoise are also fed alfalfa hay or pellets, though portion sizes and frequency vary by species. The key variable across all these small herbivores is calcium balance. Alfalfa is rarely harmful in moderate amounts, but making it the sole forage for an adult animal that is not breeding or growing can lead to mineral accumulation problems over months. Most veterinary guides recommend using alfalfa as a supplement or treat for adult small herbivores rather than the primary hay source.

How Alfalfa Reaches All These Mouths

Part of the reason alfalfa supports such a diverse roster of consumers is the variety of forms it takes. Baled hay is the most traditional product, but alfalfa also comes as haylage (fermented, higher moisture forage), dehydrated pellets, cubes, meal, leaf protein concentrate, and fresh pasture. Each form suits different animals and feeding systems. Dairy barns use a mix of hay and haylage. Poultry operations buy dehydrated meal. Aquaculture facilities use processed leaf protein concentrate. Horse owners might feed cubes on a trail ride. Pet stores sell small bales of alfalfa hay bundled for rabbit cages.

The plant itself is a perennial legume, meaning it fixes nitrogen from the atmosphere through a symbiotic relationship with soil bacteria. Fields can remain productive for four to eight years before needing to be replanted. This longevity, combined with multiple cuttings per season in irrigated areas, makes alfalfa one of the highest-yielding forage crops per acre. The sheer volume produced globally ensures there is enough to feed dairy herds, supplement beef cattle, enrich poultry diets, experiment with fish feeds, attract wild game, and sustain pet rabbits, all simultaneously. Few plants serve so many roles across so many species, and fewer still manage to be both a staple crop and a frequent source of headaches for farmers trying to protect it from the wildlife and insects that want their share.