The Way of Horses - Horses and Alfalfa

August 1, 2013
Eleanor Blazer
Eleanor Blazer
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By Eleanor Blazer
Copyright @ 2013

Horses and Alfalfa

Is alfalfa best hay for horses?
The word alfalfa comes from the Arabic word “alfasfasha”. Loosely translated it means “the best fodder”.
But, is it?
Alfalfa is high in protein. Crude protein of alfalfa harvested during the bud stage can be as high as 19.0 – 20.0 percent. First cutting alfalfa harvested late (during late bloom) can still have a protein level of 12.0 percent.
Mature idle horses require approximately 8.5 percent crude protein each day. At the high end a nursing foal requires 18.0 (provided by mother’s milk or a creep feed); a weanling may need 16.0 percent, with most other classifications of horses needing 10.0 to 14.0 percent crude protein.
Protein can create excessive body heat during digestion, increased energy and wet stalls.
The high protein content of alfalfa makes horses drink more water. This produces more urine; resulting in wet stalls. Protein will not damage the kidneys, but if a horse already has kidney damage they will not do well on alfalfa (or any other high protein product.)
The major problem with alfalfa is the high calcium and low phosphorus content. Horses need about 1.5 to 2.0 parts calcium to 1.0 part phosphorus. Alfalfa may have a ratio of 6.0 parts calcium to 0.15 parts phosphorus. This is not good and can be one of the causes of physitis and contracted tendons in growing horses.
Compare these numbers to bluegrass hay: 1.0 part calcium to 0.97 parts phosphorus; pre-bloom timothy hay: 2 parts calcium to 0.50 parts phosphorus or orchardgrass hay: 1.13 parts calcium to 0.89 parts phosphorus. (Getting closer to what we want for our horses.)
Now let’s look at the actual amount of calcium in the alfalfa hay.
According to the National Research Council’s Nutrient Requirements of Horses (2007)) alfalfa hay may contain 1.19 percent calcium (dry matter basis).
For fun let’s look at others. Bluegrass: 0.26 percent calcium; timothy (pre-bloom): 0.51 calcium; orchardgrass: 0.38 and Coastal Bermudagrass hay: 0.49.
A mature horse’s daily requirement is 0.30 percent.
How does all that extra calcium affect the horse?
Excessive amounts of calcium can cause kidney stones (renal calculi). It may also cause intestinal stones (enteroliths).
Chemical analysis done on enteroliths has shown calcium as a major component. Magnesium (alfalfa contains high amounts) is also present in the chemical make-up of enteroliths. These stones can cause colic and grow to a very large size.
Excessive amounts of calcium can also affect the parathyroid gland. The parathyroid gland controls the amount of calcium in the blood. It shuts down if there is already enough or excessive amounts of calcium being provided by diet (alfalfa). The horse then gets into trouble if there is a sudden drop in calcium (for example; during strenuous exercise) – the gland is not working so does not detect the need for more calcium.
This deficit in calcium can cause muscle cramping (tying-up), soreness, and a syndrome called “thumps”. Thumps occur when the phrenic nerve fires erratically because of the lack of calcium. The nerve leads to the diaphragm and causes it to “jump” making the horse act like it is hiccupping.
Alfalfa is one of the top commercially produced forages in the United States. It grows well under irrigation, is easy to market; horses like the taste and horse owners like feeding it.
If you want to feed a little alfalfa a good rule of thumb is don’t feed more than 30% of the forage as alfalfa. When mixed with grass hay at this ratio, the nutrients will be closer to what is recommended.
Do not feed moldy or dusty hay to horses. Try to find bales that contain more leaves than stems (the nutrients are in the leaves). Ask your supplier if the alfalfa is blister beetle free – blister beetles kill horses. For more about blister beetles please visit:

* For information about caring for and feeding horses take the online courses “Stable Management” and “Nutrition for Performance Horses” taught by Eleanor Blazer. Earn certification or work toward a Bachelor of Science degree in equine studies. Go to for more information. Visit Eleanor's web site at