Haylage is a fermented forage product made from grass or legumes that have been cut, partially wilted, and then sealed in airtight wrapping to undergo anaerobic fermentation. It sits between traditional hay and silage on the moisture spectrum — drier than silage and moister than hay — and has become a popular alternative forage for horses across the UK, particularly in wetter climates where making good quality hay is difficult.
How Haylage Is Made
The production process begins with cutting the grass at the right growth stage — typically when it is leafy and nutritious but before it becomes too stemmy. The cut grass is left to wilt in the field for a shorter period than hay (usually 24 to 48 hours compared to several days for hay), reducing its moisture content to around 40–60%. It is then compacted tightly into bales and wrapped in multiple layers of plastic film or sealed in silage bags to exclude air.
Once sealed, naturally occurring bacteria begin to ferment the sugars in the grass, producing lactic acid. This acidic environment preserves the forage, preventing the growth of moulds and harmful bacteria. The fermentation process is complete within a few weeks, after which haylage can be stored for many months as long as the wrapping remains intact.
Nutritional Profile Compared to Hay
Because haylage is cut earlier and dried less, it typically retains more of the plant’s original nutrients than hay. It tends to be higher in digestible energy, protein, and certain vitamins. The moisture content — typically 25–50% for horse haylage — means horses consume less dry matter per kilogram of feed, so it is important not to feed haylage weight-for-weight with hay. A common guideline is to feed approximately 20–30% more haylage by weight to provide the same dry matter intake as hay.
The higher moisture content also contributes to horses’ daily water intake, which can be beneficial for horses prone to dehydration or those that drink poorly. However, owners should be aware that very high moisture haylage can be fermented to the point where it is more similar to silage, which is generally not appropriate for horses due to its very low pH and potential for listeria contamination.
Benefits and Considerations for Horses
Haylage offers genuine advantages for several horse types:
Horses with respiratory conditions: The moisture in haylage means dust and mould spores are far less prevalent than in dry hay. For horses with equine asthma (RAO), chronic cough, or inflammatory airway disease, haylage is often the recommended forage. See also the haylage for horses feeding and storage guide on this site for practical advice.
Performance horses: The higher energy density supports horses in hard work without requiring large quantities of hard feed.
Young and elderly horses: The softer texture and improved digestibility make haylage easier to chew and process, benefiting horses with dental issues or those needing higher nutrient availability.
The main considerations are cost (haylage bales are typically more expensive than equivalent hay), the need to use bales quickly once opened (three to five days in warm weather to prevent secondary fermentation), and the risk of overfeeding rich haylage to good doers or horses prone to laminitis.
Storage and Handling
Intact haylage bales should be stored away from direct sunlight and sharp objects. Any puncture in the wrapping will allow air in, which immediately starts the aerobic breakdown process and can lead to visible mould growth. A small puncture can render an entire bale unsuitable within days. Once opened, haylage should be stored out of rain and fed within a few days.
Always check bales before feeding. Haylage that smells strongly acidic but clean is generally fine. Any that smells putrid, has visible black or white mould, or has a slimy texture should be discarded. For further guidance on horse nutrition and horse care, the BEVA website at beva.org.uk offers evidence-based nutritional resources.
Frequently Asked Questions
Is haylage safe for laminitic horses?
It depends on the specific haylage. High-quality horse haylage made from mature grass and properly fermented can have a lower non-structural carbohydrate (NSC) content than spring hay. However, some haylage is very rich and entirely unsuitable for laminitics or horses with equine metabolic syndrome. Testing the NSC content of your forage via a laboratory analysis is the only way to know for certain. Consult your vet before making dietary changes for an at-risk horse.
How long does haylage last once a bale is opened?
Once opened, haylage should ideally be used within three to five days during cooler weather, and within two to three days in warm conditions. Exposure to air initiates aerobic fermentation, which can cause rapid heating, mould growth, and degradation of the forage. Large bales opened slowly over a week or more in summer are a common source of respiratory issues in horses.
Can I make my own haylage for horses?
Yes, but it requires specific equipment, experience, and good quality grass. The most common DIY approach is round bale haylage using a contractor to bale and wrap. The key factors are achieving the correct dry matter percentage (typically 45–60% for horse haylage), applying sufficient layers of wrap (minimum four), and ensuring bales are sealed without air pockets. Poor fermentation producing silage-level acidity or contaminated bales can be fatal to horses, so small-scale production carries real risk without proper knowledge.