When to Start Spring Grazing

It is tempting to turn horses out into spring pastures at the first sight of green grass, especially after a long winter. However, spring grazing should be introduced slowly and delayed until grasses reach 6 to 8″ to optimize both the health of the horse and pasture. When horse pastures reach 6 to 8″, begin grazing for 15 minutes, increasing the grazing time each day by 15 minutes until 5 hours of consecutive grazing is reached. After that, unrestricted grazing can occur.

Why is this recommendation so important? Even though hay and pasture are both forms of forages, there are significant differences. Dried hay is approximately 15% moisture compared to fresh pasture that is 85% moisture. The horse is a hind-gut, fermenting herbivore that relies extensively on the microbes present in its gastrointestinal tract to be able to process forages. The microbes are a mix of different organisms that work together to the benefit of the horse. If the feedstuffs the microbes are utilizing change suddenly, there may be too little time for the microbial populations to adjust to the change. Instead, large numbers of them die, while others flourish, setting up a situation where toxins may be absorbed by the horse, resulting in digestive dysfunction and possibly colic. A gradual change from one feedstuff to another provides enough time for the microbial populations to adjust.

Additionally, pasture grasses need sufficient growth before grazing is allowed. Photosynthesis (the process of converting solar energy to chemical energy) occurs mainly within the leaves of plants. If the leaves are grazed too early (prior to 6″ tall) or too often, plants can lose vigor, competitiveness, and root structure due to the lack of photosynthetic ability. This will lead to eventual die back and overgrazed areas being replaced by undesirable plant species or weeds. Grazing should cease when forages have been grazed down to 3 to 4 inches. At this time, move horses to another paddock or a dry lot. Grazing can resume when grasses regrow to 6 to 8″. On average, about 2 acres of well-managed pasture can provide the forage needs for one horse during the grazing season.

It is critical to slowly introduce horses to spring pastures. So, the following is worth repeating, when horse pastures reach 6 to 8″, begin grazing for 15 minutes, increasing the grazing time by 15 minutes each day until 5 hours of consecutive grazing is reached. Following this recommendation will help ensure both horse and pasture health.

Author and photo credit: Krishona Martinson, PhD, University of Minnesota

4 Replies to “When to Start Spring Grazing”

  1. Help!!! I live in Central CA and have native Bermuda which only gets to 4″. Maybe 10 years from now it will be 6″. Also, we flood irrigate every 2 weeks. What does your research show for Bermuda and not Blue Grass or Rye? My weeds get taller than this grass. My hay is TEFF hay when in their stalls for the evenings. Thank you

    1. Well i didn’t do that and now with moderate to severe soreness. I should’ve known. But didn’t know about the 15 minute increments

    2. Hi Barb, Thanks for the question. The minimum recommended grazing height for Bermudagrass pasture is 2”, with the ideal initial grazing height being 4-5”. Bermudagrass pastures also do best with rotational management and each pasture should have a rest or recovery period of 2-3 weeks before horses are turned back out. Hope that helps!

  2. Our ten year old quarter horse foundered due to grazing and what we were feeding her. Two vets told us she should be put down. A third one Amy Walton differed. She recommended Safe Choce for mature horses and hat twic a day. That was 15 or more years ago and our Baby Sister is still doing fine. We only let her graze a few hours daily now as she approaches old age. You may choose to use this story.

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