Pasture grass and NSC values


The risk of laminitis is always higher for the horse with Cushing’s disease or Equine Metabolic Syndrome (EMS), which includes Insulin Resistance. Higher “sugar” levels in pasture, the NSC value, can more easily trigger laminitis in compromised horses.


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Is pasture grass good for all horses?


  • This will depend on a few things, the first being your veterinarian’s input. Some horses with Cushing’s or IR that have well-managed and monitored conditions may be able to have some nibbles of pasture.


many rolling fields with lush green pasture

All of the salad. So delicious, but not best for every horse.


What is the NSC value?


  • A few basics about pasture grass and “sugars”. I’ll refer to “sugars” as NSC, non-structural carbohydrates, which include simple sugars, starch, and fructan.


  • It should be noted that cool-season grasses (like bluegrass, rye, fescue) collect fructan, simple sugars and starch. Warm-season grasses (like bermuda, st. augustine) collect simple sugars and starch. We worry about NSC because it can induce laminitis, and if your horse is metabolically compromised, this risk increases.


What does the NSC content of your pasture grass depend on?


  • Weather. When there is plenty of sun and water for grass to grow, it will. When there is drought, cold nights below about 40 degrees F, hot direct sun, the NSC will increase as the grass stores NSC to overcome its conditions. Shade is a wonderful way to reduce NSC in pastures.


sparse grass near a fence

This sparse and short pasture is better for horses.


  • Type of grass. Cold or warm season, grass or legume, a blend of grasses, how many weeds (dandelions and thistles are super high in NSC and delicious to horses) all affect the NSC levels.


  • Growth stage. Is the grass in its baby stages? Or has it gone to seed? When grass goes to seed, it has stored massive NSC in the seed heads, which is why our horses love to eat them!


  • In general, the NSC will increase when the grass is stressed out. There’s bad weather, there’s little water, finals are coming up and it hasn’t studied, you get the idea.



very long and lush pasture grass

This long and lush pasture may look like “JACKPOT” when in fact it’s not ideal.


The best times for your horse to graze


  • During warm months, graze in the mornings. High temps and hot sun create high NSC levels in the afternoon.


  • In cooler months, graze in the afternoons if the weather has been below 40 degrees F overnight.


  • Avoid using the pastures after mowing. Wait a day or two after mowing.


  • Avoid grazing on pastures that have been allowed to grow too long.


  • Avoid dead and dying pasture grass, similar to drought conditions. This creates a plant that is hanging for dear life and will store NSC like mad.


  • Shade your pastures if you can. Shade reduces NSC levels.



gray horse in paddock catch pen by the gate

This dry lot or catch pen has some nibbles, but not so much that sugar-sensitive horses will overdose on NSC’s.


Remember that we need to balance keeping our horses natural and as close to wild as we can while working within the constraints of modern horse keeping.


  • Feral horses do not have supplements, hay meals, and rich pasture. They have prairies with sparse grass and slim pickings and thousands of acres. We have densely packed pastures filled with modern-type grasses on portions of acres if we are lucky.


horse in brown fly sheet grazing on brown dry grass

This grass, turning brown in spots, is stressed out and has higher NSC values. Not ideal for some horses.


Tips for safer grazing



  • During times when your pasture grass is stressed, supplement with a slow feeder in a dry lot or paddock.


  • Have a dry lot available for high laminitis risk horses. This also benefits horses that rip around and shred the grass pastures.


  • Acclimate your horse to pasture eating and living slowly. Start with 15 minutes or so per day, then gradually increase by a few minutes every few days or so. Even if your horse has pasture year round, high-risk seasons like spring and fall may warrant you adjusting grass pasture times.


  • Work with your Veterinarian, Equine Nutritionist, and local Agriculture Extension Agency for help! Take advantage of it!


roan horse wearing a black greenguard grazing muzzle

Grazing muzzles, like this Greenguard Equine Muzzle, are helpful for high-risk horses.


How do you handle the fluctuating NSC values in your pasture? Do you do anything differently for your high laminitis risk horses?

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