Abundant in protein and calcium, alfalfa is a good source of forage for young, growing horses and lactating mares. For most other horses, it can be too rich and lead to obesity. The high protein concentration can lead to excess nitrogen intake, which is excreted in the urine, causing a pungent ammonia smell in the stable. Western states in particular grow a lot of alfalfa and tend to feed it in the form of hay cubes because baled hay is harder to come by in these areas.

Closeup of horse eating hay

Another drawback to keep in mind if feeding alfalfa hay is blister beetles, which produce a poisonous substance called cantharidin that is toxic when fed to horses. Be sure to break open a few flakes and inspect them for traces of blister beetles before purchasing alfalfa hay.

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This article originally appeared in the 2010 issue of Horses USA. Click here to purchase a copy.

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Holly Caccamise has been with Horse Illustrated and Young Rider since 2007, and in August 2019, she took over as head editor. She’s been instrumental in the production of both magazines and helped Horse Illustrated win a 2018 American Horse Publications Media Award in the General Excellence Self-Supported Publication (circulation 15,000 and over) category. Before getting involved in the editorial side of print media, she worked as an award-winning ad copywriter for Thoroughbred Times magazine. Caccamise has her MS in Animal Science from the University of Kentucky, where she studied equine nutrition and exercise physiology, and her Bachelor’s from UCLA in Biology. Caccamise has also worked as a research assistant, horse camp counselor teaching riding and vaulting, and as a top-level show groom in the eventing world, where she continues to compete her horse, Artie, at the lower levels.


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