Quick Answer
A roughage analysis is the most reliable way to determine the sugar, protein and energy content of hay and haylage. Research based on more than 30,000 forage samples shows that forage can vary considerably between samples, making it impossible to accurately assess nutritional value by appearance alone. Knowing these values helps horse owners make more informed feeding decisions and tailor diets to individual horses
Why Is Forage Analysis Important?
Forage, including hay and haylage, forms the foundation of most horse diets and provides the majority of a horse's daily nutrient intake. Because roughage contributes so much to overall nutrition, its quality can directly affect a horse's health, body condition and performance. Many horse owners evaluate forage based on colour, smell and texture. While these factors can provide useful indications of cleanliness and overall quality, they do not always reveal underlying hygienic issues or contamination. In some cases, roughage may appear and smell normal despite the presence of mould, dust or other undesirable contaminants. Laboratory analysis provides objective information about the nutritional composition of roughage, while hygienic testing can offer measurable insights into forage hygiene and potential contamination risks. Without laboratory testing, both the nutritional and hygienic quality of roughage may remain uncertain.
Not All Roughage Is the Same
Recent research analysing over 30,000 hay and haylage samples collected in Germany, Belgium and the Netherlands between 2016 and 2025 highlights just how variable forage can be. Even forage samples that appear similar can differ substantially in sugar, protein and energy content.
Research Shows Changes in Forage Nutritional Value
Over the ten-year study period (2016-2025), several trends emerged in forage nutritional composition:
- Average energy values declined over time.
- Average crude protein levels also decreased.
- Sugar levels showed substantial year-to-year variation.
- One commonly used reference value for roughage is 100 g sugar/kg dry matter (10%), particularly when assessing forage suitability for horses that require careful sugar management. The proportion of roughage samples exceeding this threshold gradually increased during the study period.
Although individual roughage samples still show significant variation, these findings demonstrate why forage testing is becoming increasingly valuable for horse owners.
Why Are Sugar Levels in Roughage Important?
One of the most important findings from the research was the continued presence of moderate to high sugar concentrations in many forage samples. For horse owners, this matters because sugar intake can influence how suitable a forage is for certain horses. The key point is that hay with a similar appearance can contain very different sugar levels. Without analysis, it is impossible to know whether a roughage is suitable for horses that require controlled sugar intake. A common misconception is that roughage with lower energy levels will automatically contain less sugar. In reality, roughage can provide relatively little energy while still containing significant amounts of sugar. Current roughage data illustrate just how variable sugar concentrations can be. In a recent analysis of nearly 2,000 forage samples from summer 2026, 58% contained more than 100 g sugar/kg dry matter, of which one-third exceeded 120 g/kg dry matter.
Which Horses Benefit Most from Knowing Forage Sugar Levels?
Hay analysis is especially valuable when selecting forage for horses with metabolic challenges. This includes horses with:
- Equine Metabolic Syndrome (EMS)
- Insulin dysregulation or insulin resistance
- PPID (Pituitary Pars Intermedia Dysfunction)
- A history of laminitis
- Excess body weight
- Easy keeper tendencies
For these horses, forage sugar levels often play an important role when creating an appropriate feeding plan.
Why Does Protein Content Matter?
Protein provides the amino acids required for many essential functions within the horse's body. Adequate protein intake supports:
- Muscle maintenance and development
- Growth in young horses
- Tissue repair and recovery
- Healthy coat development
- Seasonal coat changes
Recent seasonal data showed that approximately two-thirds of forage samples contained less than 92 g crude protein/kg dry matter. As a result, roughage may contribute less protein to the diet than many horse owners expect, making forage analysis an important step when balancing the overall ration. However, crude protein only measures the total amount of protein present. It does not indicate how effectively that protein can be utilised by the horse. This means that roughage with a seemingly adequate crude protein value does not automatically provide all the usable amino acids a horse requires. Forage results should therefore always be interpreted within the context of the complete diet.
Energy Content Should Not Be Overlooked
Every horse has unique energy requirements. The energy needs of a competition horse differ from those of a leisure horse, while growing horses and senior horses may have completely different nutritional demands. Because roughage supplies the majority of a horse's daily calories, knowing its energy content helps determine whether additional concentrate feed is necessary. This can help avoid both underfeeding and unnecessary calorie intake. If roughage contains less energy than expected, additional sources of calories may be required to support condition and performance. Conversely, when roughage already provides sufficient energy, some horses may require little or no additional energy from concentrate feeds. A forage analysis helps determine the contribution your forage makes to the overall diet.
Benefits of Roughage Testing
Testing your forage can help you:
- Understand the nutritional value of your hay or haylage
- Assess sugar, protein and energy levels more accurately
- Adapt feeding programmes to individual horses
- Avoid unnecessary supplementation
- Support horses with metabolic concerns more effectively
- Improve ration balancing and nutrient management
The result is a feeding strategy based on measured data rather than guesswork.
Conclusion
A roughage analysis provides objective information about the sugar, protein and energy content of hay and haylage. Because nutritional forage quality can vary considerably between samples, laboratory testing provides objective insight into the nutritional profile of forage. Before selecting concentrates or supplements, it makes sense to understand the nutritional profile of the roughage that forms the basis of your horse's diet. Knowing what's in your roughage allows for more precise, individualised feeding decisions and helps ensure that your horse's nutritional needs are met.
Source: Bos et al., 2026. Forage nutrient composition and its relevance to dietary management in healthy and insulin dysregulated horses: A retrospective study. Animal - Science Proceedings, 17(2), 168-169. https://doi.org/10.1016/j.anscip.2026.06.032
