Debate Haylage or Hay

What are the differences between haylage and hay?

What is the difference between haylage and hay?

Ever wondered what is the real difference between haylage and hay? After all they are both grass and maybe smell a little different but what is the difference?

Horses require forage all year round but grass growth is seasonal and therefore there are 2 main preservation methods that help keep forage good to eat all year round.

The 2 methods of forage preservation are:

1.    Fermentation – where the pH is reduced and the growth of bacteria pauses. This is haylage.

2.    Dehydration – where moisture content is reduced to weaken microbial activity. This is hay.

Preservation methods and dry matter (DM):

Both methods of preserving grass result in different levels of dry matter.  Hay is preserved through dehydration and therefore has high dry matter content and lower moisture content.  The level of dry matter for hay is approximately 80% in comparison to haylage which is between 40 and 60%.

Digestibility and yields:

Essentially, the more advanced grass growth becomes, the higher the potential yield for the grower.  However, a more mature grass has higher levels of lignin and the purpose of lignin is for the complex building structure of grass.  The more mature the grass the stronger the lignin is, making the grass less digestible.

Young grass with low levels of lignin is much more digestible and this is why horses are turned out on grass in springtime.  However if haylage or hay were to be harvested at this stage of growth, yields would be poor and not economical for the grower. There is a point between these two stages where digestibility and yield can be balanced.


Haylage and hay are typically cut at different times of the year.  For example haylage is cut around mid-June and hay between May and July.  With haylage the grower must ensure there is enough moisture content in the forage to complete the fermentation process to make what we know as haylage.  Therefore later cuts for haylage are difficult because of the high lignin content.

As always harvest times depends on location including: altitude and climate.  Areas in a higher altitude are typically cut later than those in lower levels.

To aid your buying decisions for forage here’s a few interesting points to remember.  Forage advertised by “cut” generally means the forage was cut early or late, first or second.  Often hay can be cut from the same field up to 4 times in the right climate.

Understanding the differences between “cuts” can help you make better buying decisions.

Forage referred to as first, second, third and even fourth cut tells you whether the forage is the first crop taken or a subsequent cut from a particular field.

The most important point to remember is the maturity of the grass when it is cut because this directly corresponds with the nutritional value.  Often the grass variety influences this and the grower should have good knowledge and understanding to advise you.


Hay needs around 30 hours of sunshine which can be tricky to achieve in the UK.  The risk of losses in hay quality during the curing process often makes it difficult to source high quality hay.  Haylage on the other hand only requires 1-2 days before baling.

Baling Haylage:

Once baled haylage needs to be wrapped within 4-6 hours to avoid losses in quality.  The air is sealed out of the bale by using a plastic wrap of around 6 to 8 layers.  If air were to penetrate the bales through holes or incorrect wrapping, mould will grow and eventually the bale will become unusable.  By sealing the air outside the bale, it creates an anaerobic environment inside the bale which pauses microbial growth and activity.

Lactic acid bacteria ferment water soluble carbohydrates into organic acids within anaerobic conditions.  This acid decreases the pH from around 6 to 4 which again halts the growth of microbes.  At this point the forage is stabilised and preserved.  A lack of water soluble carbohydrates (WSC) or moisture results in incomplete fermentation.

The whole process usually takes around 3 to 6 weeks.

Storage and Feeding

Hay is not wrapped so it should be stored in a dry, well-ventilated area raised above the ground. Haylage is wrapped and therefore can be stored outside.

Usually hay is left to cure for 4-6 weeks before feeding to make sure microbial activity stops.  However in cases where moisture content is low and dry matter (DM) is above 86% it can be fed straight away.

If hay is stored properly it can be fed after several years, but obviously nutrition will be lost over time.  It may also be dusty and require steaming.

On the other hand haylage needs time to ferment so it should not be fed straight after wrapping.  Allow approximately 6 weeks for the fermentation process to complete before opening.  Once opened haylage must be used within 3-6 days (depending on the type of haylage and time of year).

It is worth noting that high temperature steaming can help to extend this ‘shelf-life’.

Choosing hay or haylage:

Haylage is often chosen in preference to hay because it is perceived to contain less dust and spores.  However, haylage at 50% moisture to dry matter contains only diluted nutrients as a proportion of the haylage is made up of water.  Therefore, horses need 1.5 times the amount of haylage than if fed on hay.  The perception that haylage is “richer” because it looks or smells better leads many people to feed smaller quantities.  Yes, haylage can be richer and more digestible (as generally cut earlier) but the nutrients are diluted.  So to meet the requirements for a healthy horse generally they need more haylage in comparison to hay.

Hay is high in dry matter which brings with it higher levels of respirable dust and spores.  However, the dry matter is a big advantage because the nutrients hay contains are not diluted.  Soaking hay is a popular way to “damp down” respirable dust and spores however the water dissolves the precious nutrients in the hay leaving you with fibre and effluent!

On the subject of forage hygiene:

Haylage has a higher moisture content and many assume it contains little to no respirable particles but this is not true.  Although in smaller quantities than found in hay, haylage does contain repiratble particles such as dist and mould which doesn’t make haylage more hygienic than hay.  However, just like hay, haylage can be steamed to improve its hygiencic quality.

Forage feeding in the 21st Century

Hay is becoming a less attractive crop for growers because poor weather windows for harvesting the grass are often small.  Haylage on the other hand is easier to produce in comparison which may mean that good quality hay will be harder to find in the future.

Growers that focus on forage for horses often have a good knowledge of horses and produce a quality consistent crop for them.

The invention of steamers has afforded more flexibility in feeding hay. With sometimes questionable quality, steaming allows these forages to be fed with much improved hygiene, where in some cases they may have been unsuitable to feed. The introduction of steaming could not have come at a better time considering the challenges we face with hay production.

Making the Decision

Your choice of forage should not only be based on which type of forage may be most suitable, but also what forage you can reliably source of good consistent quality.

As forage should comprise the majority of any horse’s diet, knowing a little more about where you source forage from and what questions to ask from the provider is key in ensuring you make the best feeding decisions.

Lastly, once you’ve made your decision, always remember to properly transition you horse from one forage to another –even if it is just a different batch of hay or haylage. Changes in forage are reported to result in a greater risk of colic than changes in concentrate feed.


Got your chosen forage? Do you soak or steam?


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