Benefits of grazing horses at night

Horses grazing at night can be a tool to beat heat, bugs, and weight gain.

The night turn-up is a much-welcome relief from pesky flies and the sweltering heat of hot summer days. It is also a great way to keep horses on grass for extended periods of time while reducing the risk of weight gain.

“Night grazing is a tool for managing horses on pasture to keep them from putting on weight,” said Katie Watts, plant biologist, former agricultural researcher and owner of, a company focused on managing sugars in grasses. “The natural cycle for pasture plants is that when the sun goes down the plants stop photosynthesizing and producing sugar. As the night progresses, they (plants) use the sugars (they produce during the day) to grow.”

A metabolically normal horse—one that is not insulin resistant, cushingoid (having a pituitary gland dysfunction, or PPID), or laminate—can handle eight hours of daytime pasture but is starting to gain a lot of weight and will benefit from a nighttime turnout.

“I’m a big believer that there’s a lot of good in pasture that you can’t get in hay,” said Watts. “And I’ve always been an advocate of allowing horses as much access to pasture as possible as long as they don’t get fat. It’s not healthy to be obese.”

These guidelines are for North American summers when plant cycle (daily) sugars are lowest at 3 a.m. and begin to rise again after sunrise. At extreme latitudes, as in places like Scotland or Alaska, the diurnal rhythm is compressed, and longer daylight hours mean that plants produce sugars until late at night.

Another low-sugar alternative for night grazing is to get the horses out of the pasture early in the morning, around 6 am, and bring them in around 10 am when the plant’s sugar production is up again. “This is especially helpful if you’re a morning person,” Watts said. “It all depends on when people go to work and their sleep cycle. If you’re an early riser, it might be best to get up earlier and put her out for a few hours and then again (put her out) in the evening.”

Once overnight temperatures drop below 40 degrees, beware of nocturnal grazing. “When we have a hard frost, the (summer growth) cycle ends, and sugar levels will stay high through the night,” Watts said. The end of summer signals a difficult cessation to night grazing for most horses, especially those with metabolic conditions such as PPID or laminitis.

Because PPID horses often have issues regulating insulin, reducing sugar in these individuals’ diets is usually beneficial. Along with your vet’s advice, limited grazing in the early morning may be the safest option for them. It could be a way to allow them an extended turnout time without compromising their safety and preventing them from needing a dry place.

Just be “committed and flexible,” Watts said. “Are your horses getting fatter or thinner?” Adjust your grazing schedule accordingly.

Tips for grazing horses at night

If you have horses that might benefit from night grazing, see the do’s and don’ts:

I do:

  • Secure perimeter fencing, and ensure all gates are closed properly.
  • It provides plenty of fresh water for the horses in the grazing area. Studies of other livestock show that animals graze more and are less likely to test the fence when they have both food and water.
  • If mosquitoes or nocturnal insects are a problem, use fly repellent before turning horses away.
  • Implementation of rotational grazing program to avoid overgrazing. The greatest amount of sugar in shortgrass plants is in the bottom 3 inches, or seed tip in tallgrass. For further assistance in designing a periodic grazing system for your property, contact your local conservation area, extension office, or Natural Resources Conservation Service.
  • Treat each horse as an individual. Just as with people, one horse’s nutritional needs may not be the same as another horse’s.
  • Learn about a healthy weight for your horse. Seek help from a veterinarian, equine nutritionist, feed agronomist, and/or a professional experienced in the field, especially if you have a metabolically compromised individual (PPID, laminitis prone, etc.). Make any changes to the diet gradually to give your horse’s gut time to adjust.


  • Do not overgraze the pasture. The most sugar in a turf plant is concentrated in the bottom 3 inches or seed heads. Overgrazing kills grass and encourages weeds that may be higher in sugar than grass.
  • Don’t graze during cold weather (40 degrees or less), especially if it’s frost. Pasture plants store carbohydrates at very high levels during these times, making them very high in sugars and dangerous for grazing.
  • Don’t be fooled by brown grass in late summer — grasses that are brown, yellow, or dried can be high in sugars. Pasture is healthiest for horses (lowest sugar) during the active growing season when the vegetation is green and not stressed. Therefore, horses are grazed during active growing seasons (spring and summer), reducing grazing on dry pastures.

Take the message home

If your horse is metabolizing or at risk, look in this area and seek professional help. Talk to your vet about specific feeding and grazing recommendations for your horse.

“We all have to be creative,” Watts said. “We need to do what works best for our needs, the needs of our horses, and the best use of the pastures.”

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