Hay and haylage are the most common forms of preserved forage fed to horses in winter. Whilst both provide a great source of fibre for horses, they have distinct nutritional differences as a result of how each one is processed. So, what are these differences and what do they mean in terms of providing the right nutrition for your horse?
Feeding Hay to Horses
Hay is essentially dried grass. It is normally cut between May and August at a relatively mature stage of growth and left to dry out completely. As a result, the moisture content of hay is very low, but during the drying process some nutrients can be lost. The Dry Matter (DM) content of hay is around 80-95% (NRC, 2008) and the sugar content is generally around 10%, but can be significantly higher or lower depending on the species of grass cut.
The loss of nutrients and the more mature nature of hay means its Digestible Energy (DE) content makes it a low calorie forage. Hay is therefore an excellent choice for good-doers, natives and horses at maintenance or in light work, but for horses with higher energy requirements it may need to be supplemented with extra feed. Hay is great for feeding ad-lib to most horses, without the worry of potential excess weight gain.
Feeding hay to laminitic horses or ponies
For more sensitive metabolic and/or laminitic horses and ponies, however, it is often necessary to reduce the sugar content of hay, so that total Non-Structural Carbohydrates (NSC) – basically sugars plus starch, are 10% or less. Traditionally this was thought to be best achieved by soaking hay to remove sugars or Water Soluble Carbohydrates (WSC), but recent research (Longland et al., 2011) has shown that to get a notable reduction of WSC, the hay needs to be soaked for around 16 hours, by which time it is far less palatable. Furthermore, the same study found that despite a mean loss of 27%, WSC contents of 7 of the hays tested remained above the suggested upper limit for laminitic and metabolic horses (100g/kg Body Weight (BW)).
Steaming hay has been shown to significantly reduce WSC (Earring et al., 2014; James et al., 2013; Moore-Colyer et al., 2015), but results have been highly variable and in some cases the reduction in WSC may not be enough. Steaming could, however, work well for more moderate NSC hays which are not far above the ideal NSC level of 10%, with the WSC reduction from steaming bringing the NSC to within ‘safe’ limits. Low NSC hays can be produced from growing lower NSC grass species and/or cutting the hay at times when the NSC content is naturally lower, for example during the night or after cloudy weather. These hays may provide an ideal solution for laminitic and metabolic horses and ponies, without the need for soaking or steaming.
Hay – the pros and cons
Hay is economical as it is inexpensive to buy and if correctly stored will stay in good condition for a relatively long period of time. Hay is, however, prone to the accumulation of dust and mould spores, meaning it is not ideal for those horses with dust allergies, a compromised respiratory system and those that are stabled frequently.
Hay can be soaked so that the dust spores stick to the hay and are no longer airborne, but this means that they are swallowed instead of inhaled, and the quality of the hay is reduced.
Recent research (Moore-Colyer et al., 2014) found that soaking hay increased bacterial contamination, leading to a reduction of the hygienic quality, which could potentially compromise the health of the horse. Better dust reduction whilst retaining good hay quality can be achieved through steaming rather than soaking hay, as in the same study, steaming significantly reduced mould and bacterial numbers (Moore-Colyer et al., 2014).
Feeding Haylage to horses
Haylage is essentially grass that has been cut earlier and at a younger stage of growth than hay and left to wilt instead of completely drying out. This means haylage has a higher moisture content than hay and a lower DM content, typically around 50-65% (NRC, 2008).
How does the nutritional value of haylage compare to that of hay?
The lower DM content compared to hay means that a higher volume of haylage needs to be fed to ensure the horse receives sufficient fibre. This is important because adequate fibre is essential for healthy digestive function, warmth and for maintaining condition.
As a general guide, haylage should be fed at a rate of 1¼ times more than hay, but this can depend on the DM content of the haylage.
Due to its high moisture content, haylage needs to be wrapped to prevent spoilage, by creating an anaerobic environment. This anaerobic environment means that fermentation takes place which results in a drop in the pH to inhibit spoilage causing organisms.
During fermentation, sugars in the haylage are converted to lactic acid and volatile fatty acids (VFA), meaning that contrary to popular belief, haylage is normally lower in sugar than hay. Haylage is, however, higher in protein, and more digestible than hay giving it a higher DE content. As a result, horses generally tend to do better on haylage, so it’s often not ideal for overweight horses and those prone to weight gain, metabolic and laminitic horses, unless it is a high-fibre, lower DE variety. Furthermore, the acidic nature of haylage as a result of fermentation means that it may not be ideal for those horses with gastric ulcers or hindgut sensitivities.
Why choose Haylage?
Haylage is great for horses in regular work, young horses with greater energy and protein requirements for growth and older horses who need an easily digestible source of forage.
Although haylage is generally more expensive to buy than hay, its higher digestibility means that the reliance on extra feed in winter can be reduced, making it quite cost effective. This also means that with haylage, horses with higher energy requirements can potentially be well maintained on a 100% forage diet, provided their micronutrient needs are met with a suitable, wholesome balancer.
Additionally, haylage is dust free so is an excellent choice for horses with a compromised respiratory system. Once haylage is opened, however, it must be used within a few days so it is not always economical for owners who have only one or two horses.
The most important factor when choosing hay or haylage is to make sure that it is good quality. Hay and haylage have different benefits which need to be considered alongside the horses’ individual nutritional requirements. Feeding both, however, is often a great way of adding variety to your horse’s diet and can help encourage natural foraging behaviour.
Earing, J.E., Hathaway, M.R., Sheaffer, C.C., Hetchler, B.P., Jacobson, L.D., Paulson, J.C. and Martinson, K.L. (2013) Effect of steaming on forage nutritive values and dry matter intake by horses. Journal of Animal Science, 91, pp5813-5820.
James, R. and Moore-Colyer, M.J.S. (2013) Hay for Horses: The nutrient content of hay before and after steam treatment in a commercial hay steamer. Proceedings of British Society for Animal Science Conference, Nottingham.
Longland, A.C., Barfoot, C. and Harris, P.A. (2011) Effects of soaking on the water-soluble carbohydrate and crude protein content of hay. Veterinary Record, 168(23), Available from: https://veterinaryrecord.bmj.com/content/168/23/618.short?ssource=mfr.
Moore-Colyer, M.J.S., Lumbis, K., Longland, A. and Harris, P. (2014) The Effect of Five Different Wetting Treatments on the Nutrient Content and Microbial Concentration in Hay for Horses. PLoS ONE 9(11): e114079. Available from: https://journals.plos.org/plosone/article?id=10.371/journal.pone.0114079.
Moore-Colyer, M.J.S., Taylor, J.L.E. and James, R. (2015) The Effect of Steaming and Soaking on the Respirable Particle, Bacteria, Mould, and Nutrient Content in Hay for Horses. Journal of Equine Veterinary Science, 39, pp. 62-68.