Alfalfa hay typically contains 16 to 22% crude protein on a dry matter basis, with top-quality cuts reaching above 22%. That makes it one of the most protein-rich forages available, carrying roughly twice the protein of timothy hay and enough per ton to rival two-thirds of a ton of soybean meal. The exact protein content of any given bale depends on when it was cut, how it was cured, and how much leaf material survived the baling process.
Protein Content by Quality Grade
The USDA grades alfalfa hay into five quality tiers based largely on crude protein percentage:
- Supreme: above 22% crude protein
- Premium: 20 to 22%
- Good: 18 to 20%
- Fair: 16 to 18%
- Utility: below 16%
These grades apply to hay with no more than 10% grass mixed in. Once grass content climbs higher, the protein percentage drops and the hay falls into a separate grading category. A hay test from a forage lab is the only reliable way to know exactly where a specific lot falls, since color and leaf retention alone can be misleading.
What Affects Protein Levels
Maturity at cutting is the single biggest factor. Alfalfa cut in the early bud stage holds more protein in its leaves, which is where the plant concentrates most of its amino acids. As the plant matures toward full bloom, stem-to-leaf ratio increases and protein drops. First cuttings tend to be more stemmy, so second and third cuttings often test higher in crude protein even though they yield fewer bales per acre.
Handling matters too. Leaves shatter easily during raking and baling, especially in dry, windy conditions. Since the leaves carry the bulk of the protein, every lost leaf lowers the overall protein percentage of the finished bale. Rain damage during curing washes out soluble nutrients and encourages mold, both of which degrade protein quality. Properly cured, well-leafed alfalfa hay will almost always test in the Good to Premium range without any special management.
How Much of That Protein Is Actually Usable
Crude protein is a lab measurement based on nitrogen content, and it slightly overstates how much protein an animal can actually absorb. The good news with alfalfa is that its protein is highly digestible. Research from UC Davis puts the digestibility of alfalfa protein at 80 to 90%, meaning the vast majority of the crude protein on a hay test translates to usable amino acids in the animal’s body. That’s a better conversion rate than many other forages and one reason dairy and beef nutritionists value alfalfa so highly.
The amino acid profile is also relatively strong for a forage. Alfalfa contains about 1.17% lysine and 0.33% methionine on a dry matter basis. Lysine is the amino acid most often lacking in forage-based diets, particularly for horses and growing animals, so alfalfa’s lysine content gives it a meaningful advantage over grass hays.
Alfalfa vs. Other Common Hays
The protein gap between alfalfa and grass hays is substantial. Timothy hay, one of the most popular alternatives for horses, runs 8 to 12% crude protein. That means even fair-quality alfalfa delivers more protein than premium timothy. Orchard grass and bermuda grass fall in a similar range to timothy, generally topping out around 12 to 14% crude protein under good conditions.
This difference is why alfalfa is the go-to forage for animals with high protein demands, while grass hays work better for animals that need calories without excess protein. Many horse owners blend the two, using a mix of alfalfa and timothy or orchard grass to hit a moderate protein target without overfeeding nitrogen.
Matching Protein to Different Livestock
Dairy cows have the highest protein appetite of common livestock, and alfalfa is a cornerstone of most dairy rations. Lactating cows need rations in the 16 to 18% protein range, so premium alfalfa can supply most or all of the protein requirement without heavy reliance on grain-based supplements. Dairy nutritionists often seek alfalfa testing above 20% crude protein to give themselves room in ration formulation.
Beef cattle have lower protein requirements overall, but alfalfa still plays a valuable role. Feeding alfalfa at just 1% of body weight (one pound per hundred pounds of animal) supplies enough protein for maintenance along with nearly all required vitamins and minerals except phosphorus. Cows recovering from calving and producing milk for a calf benefit from alfalfa’s combination of protein and energy during that demanding period. One ton of alfalfa hay contains as much digestible energy as 25 bushels of corn, making it a dual-purpose feed.
Horses are more complicated. Performance horses, lactating mares, and growing foals benefit from alfalfa’s protein and lysine content. But mature horses in light work can easily get more protein than they need from straight alfalfa, which means their kidneys process and excrete the excess nitrogen. The result is ammonia-heavy urine and a stronger barn smell, not a health crisis, but a sign you’re feeding more protein than the horse requires. For these easy keepers, a 50/50 alfalfa-grass mix or straight grass hay is often a better fit.
Reading a Hay Test Report
If you’re buying alfalfa by the load or managing livestock rations, a forage analysis is worth the $15 to $30 it costs. The number you’re looking for is crude protein (CP) expressed as a percentage of dry matter. Some labs also report acid detergent fiber (ADF) and neutral detergent fiber (NDF), which tell you about digestibility and intake potential, but protein is the figure most buyers focus on first.
A few things to watch for: protein reported on an “as-fed” basis will be lower than the dry matter number because it includes the weight of moisture in the hay. Always compare results on a dry matter basis to get an apples-to-apples comparison. And if protein tests unusually high (above 24 to 25%), check whether the hay was rained on and then dried. Mold and fermentation can inflate nitrogen readings without adding real nutritional value.