Response: Horses can graze alfalfa. However, the major issue with pasturing horses in a mixed alfalfa grass pasture is the possibility of excessive weight gain. Even an all grass pasture can have excessive energy for adult horses at maintenance and light work, adding in alfalfa provides even more energy.
As with any pasture, introduce horses slowly and delay grazing until forages reach 6 to 8” in height to optimize both the health of the horses and pasture. When pastures reach 6 to 8”, begin grazing for 15 minutes, increasing the grazing time each day by 15 minutes until 4 to 5 hours of consecutive grazing is reached. After that, unrestricted or continuous grazing can resume.
Alfalfa is not as tolerant to frequent grazing and mowing compared to cool-season grasses (i..e orchardgrass, bromegrass, bluegrass). It is likely that over time and with good pasture management, the alfalfa will continue to thin and the grasses will continue to thicken.
There are a few things you can do to if your horse(s) start gaining weight. Keep an eye on body condition score. Adult horse body condition score should not exceed 6 (out of the 9 point Henneke scale). If horses start putting on excessive body weight, use a grazing muzzle or restrict grazing to 6 to 8 hours a day (without feeding additional hay).
Finally, if any of your horses are hard keepers or have elevated nutritional needs, the mixed grass-alfalfa pasture will be ideal.
By: Krishona Martinson, PhD, University of Minnesota