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.
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.
Back to Horse Health Glossary
Back to Equine Nutrition A to Z
This article originally appeared in the 2010 issue of Horses USA. Click here to purchase a copy.