Feed hay or haylage to your horse?

5 August 2022 - Livestock

What is the difference between hay and haylage? And when can I have the roughage sampled? Eurofins regularly receives these questions from the horse sector. 

Roughage is an important source of energy for horses. Moreover, most of the ration consists of roughage, which horse owners often do not realize sufficiently. A good roughage intake is a must for both the absorption of nutrients and the utilization of concentrates. Is the ratio of concentrated feed/roughage out of balance? Then this can lead to unwanted health problems in your horse and the associated costs. The quality of the roughage determines how much your horse eats and how well it chews it. The feed requirement varies per horse and depends on the type, weight, age and amount of exercise it gets.

Hay and haylage are two different ways of conserving and preserving grass. Both are suitable as roughage for your horse. The different form of preservation has an effect on the quality, advantages and disadvantages of these products. We list them for you:


Hay is grass that has been preserved by drying to at least about 80-85% dry matter. Often the grass is harvested when it is in flower or just after. The crop then contains a lot of crude fibre and dries relatively quickly. A horse needs rough fibre to chew properly. Sufficient chewing has a positive influence on the digestive system. Hay hardly ferments because it contains a very limited amount of moisture. The fermentation process is almost completely stopped. Hay is therefore stable and can be stored for a longer period without problems.

Too moist hay bales 

It is important that the grass has dried long enough. Hay fires can occur when making hay bales with excessive humidity. In this process, aerobic bacteria convert beneficial nutrients into undesirable acids and the temperature of the hay rises. This can lead to the growth of unwanted bacteria, yeasts and fungi which poses a health risk to your horse. When the temperature is too high, the sugars in the product caramelize (burn) and the hay begins to smell extra. In the worst case, the temperature rises to such an extent that spontaneous combustion is a real risk, with all its consequences.


Haylage is also called grass silage or silage and is a result of preservation by fermentation. The grass is dried first, just like hay, but not for as long. We speak of haylage which is suitable for horses if it contains at least 60% dry matter. This product is popular in certain countries in Europe, because we do not always have enough hours of sunshine to fully dry the grass as we do with hay. A characteristic of haylage is that it should always be packed airtight. Once the roughage is sealed airtight, good bacteria begin converting sugars into lactic and acetic acid, among other things. Depending on the moisture content, the pH will drop until a stable value is reached. The more acidic environment stops the growth of bacteria and the silage becomes stable. A well-succeeded haylage smells good.

Risks haylage

Loss of quality occurs when the preservation process takes too long. This happens, for example, when the hay is too wet, when there is too much sand in the product (expressed as crude ash) or when the bales are not sealed airtight. Unwanted bacteria, yeasts and moulds then have room to grow. The product does not preserve well, smells sour and should be discarded. Poorly preserved haylage can cause health problems such as diarrhea and colic. It is therefore important that the bales are properly wrapped. The plastic in which the bales are wrapped is sensitive to Ultraviolet light. This makes plastic porous over time. Bales that are left outside cannot be fed for more than one year, after that the quality will quickly deteriorate. Therefore, always store bales that you want to use for a longer period of time out of the sun.

Hay and haylage can be sampled 4-6 weeks after harvest to determine feed value and quality.

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