Is hay full of sugar? Understanding non-structural carbohydrates in forage

December 26, 2025 •

3 min read

While it is a common misconception that all hay is full of sugar, forage can be the biggest source of sugar in an equine diet, often contributing between 1,000 and 1,500 grams in a typical daily ration. Therefore, understanding how much non-structural carbohydrate (NSC) content is in your hay is critical for a horse's health.

Quick Summary

Hay's sugar content, or NSC, varies widely based on grass species, environmental stress, and time of harvest. Lab testing is the most reliable way to assess NSC levels for horses with metabolic issues, as soaking can be a management tool.

Key Points

Sugar content varies: The amount of non-structural carbohydrates (NSC) in hay is not consistent and depends heavily on factors like plant type, maturity, and weather.
Forage testing is essential: To know the precise sugar level of your hay, especially for metabolically sensitive animals, a professional lab analysis is the only reliable method.
Harvest time matters: Hay cut in the early morning typically has lower sugar content than hay cut later in the day, as plants use sugar for respiration overnight.
Soaking reduces sugar: Soaking hay in water, particularly for 60 minutes in cold water, can leach out a significant portion of water-soluble carbohydrates (WSC).
Species play a role: Cool-season grasses often have higher NSC levels than warm-season grasses and may not be suitable for horses with insulin resistance.
Environmental stress affects sugar: Factors like drought, frost, or inadequate fertilization can cause plants to accumulate higher levels of sugar.
Haylage can be lower in sugar: The fermentation process in haylage production consumes some sugars, often resulting in a lower NSC product than hay.

The Truth About Sugar in Hay

It's a question many horse owners face: is hay a hidden source of high sugar content? The answer is nuanced, as not all hay is created equal. The sugar content in hay, known as Non-Structural Carbohydrates (NSC), is a critical factor for equine health, particularly for horses with conditions like insulin resistance (IR) or those prone to laminitis. Unlike simple table sugar, NSC encompasses a broader range of plant carbohydrates, including simple sugars, starches, and fructans. Fructans, stored by cool-season grasses, are fermented in the horse's hindgut and can trigger health problems if levels are too high. Therefore, understanding the factors that influence NSC is key to providing a safe diet for your horse.

Key Factors Influencing Hay Sugar Levels

Several factors determine the sugar content of any given batch of hay. These include:

Grass Species

Different grass species store carbohydrates in different ways. Cool-season grasses like Timothy and orchardgrass often have higher NSC levels due to fructan storage. Warm-season grasses, such as Teff, are typically lower in NSC.

Time of Harvest

Plants accumulate sugar during the day and use it overnight. Hay cut in the morning generally has lower NSC than hay cut in the afternoon.

Environmental Conditions

Stressors like drought, nutrient deficiencies, or frost can cause plants to accumulate sugars. A light rain or cloudy period before cutting can also affect sugar levels.

Maturity of the Plant

More mature grass with seed heads tends to be more fibrous and lower in sugar.

The Importance of Testing and Management

Since visual inspection is not reliable, laboratory testing is necessary to determine the NSC level of hay. For horses with metabolic issues, an NSC of less than 10% is often recommended.

Managing High-Sugar Hay

If hay tests high in NSC, management techniques include:

Soaking: Soaking hay in warm water for 30 minutes or cold water for 60 minutes can reduce sugar by leaching out water-soluble carbohydrates. However, this also removes minerals, which may require supplementation.
Mixing with Straw: For overweight horses, mixing hay with straw can reduce caloric intake while maintaining fiber.
Limited Grazing: Restricting pasture access, especially during high-risk times, or using a grazing muzzle is important for sugar-sensitive horses.

Hay vs. Haylage: A Comparison

Choosing between hay and haylage is important for managing sugar intake. Here is a comparison:


Feature	Hay	Haylage
Sugar (NSC)	Variable based on grass type and harvest.	Typically lower due to fermentation.
Energy	Variable; mature cuts are lower energy.	Usually higher energy due to earlier cutting and digestibility.
Preparation	Less preparation; soaking needed for dust.	No soaking for dust; proper storage critical.
Metabolic Risk	High-NSC hay poses significant risk.	Can be safer, but low-sugar varieties still recommended.

Conclusion: Responsible Forage Management

Determining if hay is full of sugar requires understanding factors like grass type, environment, and harvest time. NSC content is crucial for equine nutrition, especially for horses with metabolic issues. Testing your hay is the most reliable approach. For high-risk horses, choose low-NSC hay, manage pasture, and use techniques like soaking. Proactive forage management ensures a safe diet and helps prevent conditions like laminitis. For more information on forage analysis, consult resources like the Oregon State University Extension's guide.

Understanding the Basics of Hay Sugar

Photosynthesis and Respiration: Plants make sugar during the day and use it overnight, making early morning cutting beneficial for lower sugar.
Stressful Conditions Cause Sugar Spikes: Drought, frost, and nutrient deficiencies can increase sugar accumulation in plants.
Not All Carbs are Equal: NSC includes simple sugars, starch, and fructans. Fructans are fermented in the hindgut and can cause issues for sensitive horses.
Test, Don't Guess: Visual inspection is unreliable for NSC levels; professional lab analysis is required.
Soaking Has Trade-offs: Soaking reduces NSC but also leaches minerals, potentially requiring supplementation.
Warm vs. Cool Season Grasses: Warm-season grasses like Teff are often lower in NSC than cool-season grasses such as Timothy.
Haylage vs. Hay: Haylage is typically lower in sugar but may be more energy-dense.

Frequently Asked Questions

For most metabolically sensitive horses, a hay with an NSC content of less than 10% on a dry matter basis is recommended. Your veterinarian can provide more specific recommendations based on your horse's condition.

No, a visual inspection is not a reliable method. The color and texture of hay are poor indicators of its sugar and starch content. Only a laboratory analysis can provide an accurate reading.

Yes, soaking hay leaches out not only sugars but also important water-soluble minerals like potassium, magnesium, and phosphorus. For this reason, supplementation is often necessary when soaking hay for extended periods.

Not necessarily. While haylage is generally lower in sugar than hay due to fermentation, it can also be higher in overall energy content. For sugar-sensitive horses, it is still crucial to test haylage for its NSC levels.

Environmental stressors like cold temperatures, drought, or frost cause the plant to hoard its energy reserves rather than use them for growth. This leads to higher sugar accumulation within the plant.

Generally, hay cut at a more mature stage of growth will have lower sugar content and higher fiber. Younger, more leafy hay tends to be higher in sugar and energy.

Steaming hay is highly effective at reducing dust and respiratory irritants but is less effective than soaking for removing sugar. Soaking provides a more reliable method for lowering NSC content.

Hay made from warm-season grasses like Teff, Bermudagrass, or mature, late-cut cool-season grasses are often better choices. However, testing is always recommended to be certain.