The importance of fibre for maintaining health and well-being is widely appreciated but there are lots of different sources and types of fibre available. Knowing which one is best for a particular horse or pony is where feeding becomes an art!
The term forage is generally used to describe the parts of plants that are above the ground that contain a significant proportion of fibre. The most common sources of forage for horses are grass, legumes such as alfalfa, and cereal straw. It is important to consider that forages are not just fibre, they contain other nutrients such as protein, minerals and sugar too and it is often the levels of these other nutrients that determine the suitability of a forage for a particular horse or pony.
The climate in the UK means that it is necessary to use conserved forages at certain times of the year when availability of fresh forage is reduced. Forages may be harvested as young plants which tends to be the case for alfalfa in the UK as well as some grass or, they can be allowed to mature to create hay, haylage or even silage.
The principle of conserving forage is based on removing water or oxygen in order to stop the forage from moulding or decaying. When making hay, the water content is reduced to below 20% whereas haylage typically has a water content of between 40 and 50% which is not sufficiently dry enough to stabilize it and so it has to be wrapped in plastic to create an anaerobic (oxygen-free) environment. There is a definite trend for so-called “haylages” to be drier and a more accurate name for them is “wrapped hay”. There is an important difference between haylage and a wrapped hay and that is that a wrapped hay won’t have undergone fermentation. This is evident from the analysis results where the sugar levels in wrapped hay are exactly what we expect from hay NOT a haylage. This also means that a wrapped hay is less acidic than a haylage.
There are two main criteria that determine the quality of a forage; its nutritional value and its hygienic status or cleanliness and the two don’t always go together. Digestibility is a key concept in determining the quality of a forage. In principle, the more digestible a forage is, the more energy and to some extent nutrients, it provides to the horse. Pectin is a very digestible type of fibre and is found in higher levels in sugar beet whereas cellulose is a much less digestible type of fibre and would be abundant in hay for example. High levels of lignin, an indigestible substance that gives a plant structure, significantly reduces the digestibility of a forage. The older and taller a plant gets, the more lignin is present which is why hay is less digestible than dried grass that has been harvested when the grass is young.
Less Digestible | More Digestible | ||
---|---|---|---|
![]() | ![]() | ![]() | ![]() |
4MJ/kg DE | 8MJ/kg DE | 10MJ/kg DE | 11MJ/kg DE |
Straw | Grass Hay | Dried Alfalfa | Sugar Beet |
When it comes to the hygienic quality of forage, any material that is sun-dried such as grass hay is going to have a mould count naturally higher than materials that are dried using hot air such as chopped alfalfa. Uptake of small particles (≤ 5μm) can induce hypersensitivity in the respiratory system and lead to respiratory disease. The object of soaking is to swell the size of the dust particles so they are less likely to cause irritation in the respiratory tract.
The increase in availability of haylage (or wrapped hays) offer a less laborious alternative to soaking hay and the increased moisture content they contain tends to keep dust levels down. But as it is more digestible, it tends to do some horses and ponies too well and would result in them gaining weight. There have been several studies looking at the pros and cons of steaming. One study found sugars were only reduced by 3% in steamed hay compared to 34% in soaked hay (Moore-Colyer et al, 2014) so if you need to reduce sugar content in the hay, soaking is the most effective way to do this. However, submerging in water was found to increase the numbers of bacteria in the hay which may have repercussions for gut health. The researchers therefore advocated soaking first to reduce sugar content if necessary and then steam to deal with the microbial contamination.
Soaking hay is also done to reduce its water soluble carbohydrate (WSC) content to improve its suitability for horses and ponies with insulin dysregulation such as those with EMS, PPID or that are prone to laminitis.
If hay is being soaked to improve its hygienic status then recommendations are most commonly to soak for between 10 and 20 minutes although some advocate soaking for up to 1 hour. The key point though is that the hay should not be allowed to dry out prior to feeding so once the hay has drained it should be given to the horse.
If hay is being soaked to reduce the sugar content then there are lots of factors to consider not just the timing. Firstly the ratio of hay to water is important and current advice is to use as much water as possible to maximise the leaching of sugar. Some researchers have advocated 10 parts water to 1 part hay but this simply isn’t practical for everyone. The general principle is to use as much water as you can whilst taking into consideration the fact that water is a very precious resource – using rainwater for soaking hay is one possible solution. The other factor to consider is that warmer water will remove more sugar too. Again it is not practical for everyone to use warm water but studies have shown that around 16C was optimum for sugar removal.
If you can use lots of warm water then it is suggested around two hours will help to reduce sugar levels without losing too much dry matter from the hay. Soaking for longer starts to increase losses (Bochnia et al, 2021) so the horse then has to consume more to ensure they receive sufficient fibre intake. In warmer conditions, soaking for more than two hours is also likely to result in the hay starting to ferment and this is not desirable for then feeding to horses. Studies have shown that soaking for longer periods such as 9 hours, also increased the microbial contamination in the hay. Researchers suggest this could potentially cause digestive upsets but how significant this issue is remains to be confirmed as soaked hay has been fed for many years to lots of horses without apparently causing extensive problems. In principle, in cool conditions, it is therefore acceptable to soak hay overnight if you want to but it is important to be aware that the microbial load in the hay will be increased and more is likely to need to be fed to compensate for the dry matter lost from soaking for a long time.
Techniques for soaking hay vary but there are now specialist tanks available that have drains and that are on wheels for easy manoeuvrability. If these are out of your budget range then dustbins or even an old bath can be used too. The benefit of a bath is that it has a plug and so the used water can be removed easily without having to lift or tip heavy containers. It also means the hay can be left in while the water drains off so that it is a bit lighter by the time it needs to be used.
The recommendations for the length of time to steam hay vary according to different manufacturers of commercial steamers. In studies the steaming period was around 50 minutes. If choosing a steamer that advocates less steaming time it is worth asking what research they have done to show the shorter time frames along with the temperature of the steam is sufficient to kill the same levels of bacteria. Although shorter steam times may seem more convenient, it is important to compare their performance. Although steamers are quite expensive to purchase, their performance can not be replicated trying to steam hay yourself.
Image courtesy of Haygain
In summary, the benefits of soaking hay can be for the respiratory system or to reduce its sugar content. However, soaking hay uses a lot of water, creates a lot of waste water and increases the bacterial count within the forage. Soaked haynets can be very heavy to lift too and so it is important to weigh up all of these factors when considering if soaking hay is the most practical option for you.
The minimum amount of forage (on a dry matter basis) a horse or pony should receive each day is 1.5% of their bodyweight. Too little fibre means the gut becomes more permeable or leaky which leaves the horse vulnerable to disease – minimum forage intake is so important for gut health. If the horse gains weight or continues to be overweight when fed 1.5%, the temptation is to reduce the amount of forage fed but this compromises gut health, particularly over the longer term i.e. more than 3 months. It is therefore better to feed more of a lower energy forage such as straw than less of a higher value one!
One study by researchers in Denmark, found that a horse eating straw as the sole or predominant source of forage source was 4.5 times more likely to have gastric ulcers. What often gets lost from this study is the proportion of straw in the ration. In the UK, straw is rarely fed as the sole forage source so this is unlikely to be an issue. Recognising that straw can be useful as a low-calorie forage source for good doers, a study has been published investigating the safety of feeding 50% wheat straw. The research found no increased risk of ulcers from using 50% straw to replace haylage in the ration.
No, wheat straw is more commonly available in Scandinavia as oats aren’t grown there. In the UK oat straw is usually first choice, followed by wheat and then barley.
Additional concerns may relate to risk of impactions which largely stem from studies published in the 1980s. In more recent studies exploring different types of bedding for horses and their implications for welfare, it is apparent that if horses have access to straw bedding they do move between their hay and their bedding and so the time taken to consume their forage ration is longer. Researchers in these welfare focussed studies advocate this behaviour and highlight that those bedded on shavings do, in some cases, eat their shavings but also spend less time eating which has negative consequences for digestive health. What we want to avoid is a horse or pony eating a large amount of straw in one go and so if it’s part of a mix of forages, this is less likely to occur. If a horse or pony has poor teeth or a history of impaction colic then straw is probably best avoided if fed in long length. It may still be suitable if chopped and mixed with other ingredients in the bucket feed though. If you are in any doubt please consult your vet.
If your horse has poor dentition or a history of impaction colic then straw may not be suitable but it is worth discussing with your vet as straw isn’t necessarily any more fibrous than some late cut hays. Chopped straw may be a viable option in these scenarios or dampening to soften may help too. As with any new feed introduce small amounts and increase gradually over at least 7 days. Mixing straw with the other forage will help to reduce the amount the horse is consuming at one time – problems typically occur when a horse gorges on one ingredient so the key is to limit the amount they can consume. Horses will often pick through the mix of straw and other forage which is great as it slows their intake even further!
Some horses won’t eat straw, even if there is nothing else on offer. Whilst it might seem wasteful, mixing straw in with other forages can mean it still serves a purpose by slowing the horse down when eating as they sort the straw out from the other forage.
Calculations using typical values for forages show that if straw replaces one third of the weight of an average hay, a reduction in energy intake of 16% is achieved. Obviously replacing half of a higher quality forage such as haylage will achieve an even greater reduction. Interestingly, research suggests that to lose 0.5 unit on a 5 point body condition scoring system is thought to require a reduction in energy intake of 11-15% in the total diet. This makes straw the ideal choice for maintaining forage intake but reducing weight.
Straw has a much lower water-soluble carbohydrate (WSC) content than grass forages so it has less of an impact on blood glucose and insulin levels when eaten. This, combined with a slow rate of consumption meant that in one study, no significant increase in insulin levels occurred in horses consuming 50% straw and 50% haylage. This is really valuable information for managing insulin dysregulated (ID) horses such as those with EMS or PPID.
The hygienic quality of straw can vary, so some care is required when sourcing some for your horse or pony. Straw can be soaked or steamed but if this isn’t practical then chopped straw is available to buy in branded packaging. This will have been dust-extracted and sourced from reliable growers.
Unfortunately a lot of myths abound about different fibre sources. The following information should clarify some of the most common!
Well not themselves no but they do have a population of microbes in their digestive tract that can, and the energy the microbes release from fibre is what the horse uses as fuel for work, maintenance or growth. The other key fact is that the horse’s digestive system is designed to slow the transit of fibre long enough for the microbes to break down the fibre and release the energy – if the horse’s gut was like ours, the bugs simply wouldn’t have time to do their work before the food passed through and out of the digestive system.
Er, no it doesn’t, well not much anyway, not by the time it has become a feed for horses and other animals. The sugar has nearly all been taken out for use in human foods and what is left is a really fibrous pulp. The pulp itself is less than 5% sugar so less than half the simple sugars found in most hays. Some sugar beet pulp has molasses added to make it a little bit sweeter and more palatable but unmolassed sugar beet pulp is a really great source of highly digestible fibre with a low sugar content. The fact that it is so digestible means it is effective at promoting weight gain safely. As it is fed soaked it can be used in a dilute form to dampen feed and hide supplements for horses and ponies that require a low sugar diet.
Rich can mean different things to different people but if we take protein as a measure of richness, most alfalfa chaffs in the UK have a protein level of between 12 and 15%. This is comparable to a conditioning cube or competition mix. Most importantly a percentage of protein means nothing until it is considered in conjunction with how much is fed. One scoop of a 12% alfalfa chaff weighs around 400grams and so supplies 48 grams of protein which equates to between 6-8% of a 500kgs horse’s daily maintenance needs. Very few people feed more than a couple of scoops per day and so are only supplying around 12-16% of their horse’s total requirement – certainly not a case of being too rich for most horses! Confusion is often caused by the fact that alfalfa is used as a hay in the USA and Canada and so is fed in much, much greater quantities – maybe 10kgs a day. This fact is often missed when information is posted on the internet that relates to feeding alfalfa.
Oatfeed often causes confusion especially when it’s included in feeds for horses in light work or those prone to laminitis. Oatfeed is the fibrous hull from around the grain and is removed when the grains are processed for use in human foods such as porridge. Oatfeed contains around 25% fibre so although it comes from a cereal plant, it’s not the grain itself and so is relatively low in starch at approximately 10-12%. It is supplied in a pelleted form and so can be used to dilute other ingredients in lower energy feeds.
The horse has evolved to spend most of its time eating – up to 18 hours every day – and it is suggested that horse’s will typically eat between 2 and 2.5% of their own bodyweight per day of dry matter.
However, many consume much more; ponies can consume twice as much if left to their own devices on good pasture!
Even 2% of low nutritional value feed such as forage can be too much for some good doers. It is widely accepted that 1.5% of bodyweight dry matter should be the minimum amount of forage fed for long term management of good doers.
The simple answer is that forages do not contain all the nutrients a horse needs particularly those in work, youngsters and breeding stock. Plants reflect the soil they are grown in and as UK soils tend to be very low in trace minerals such as selenium and copper, there are not present in forages in sufficient quantities to meet a horse’s needs.
Most good doers simply need a good source of vitamins and minerals alongside their forage ration. This can be supplied in the form of a balancer or supplement. If a horse is on limited forage intake we would recommend using a high specification of supplement or balancer to make up the shortfalls in essential nutrients that forage would normally provide.
In the wild horses follow a seasonal cycle of weight gain through the spring/summer and weight loss during the winter. In the domestic environment, winter weight loss is something we should try to encourage for overweight individuals as year-on-year weight gain is likely to increase laminitis risk. As a guide, by the end of winter ribs should be easily felt and just visible so that the horse can gain a little in the spring and summer without becoming overweight.
Winter grazing and conserved forage can still provide more calories than required for weight loss and so need careful management for those that are overweight or good doers. Strip grazing, use of a grazing muzzle if the grass is long enough, or turnout on a no-grass area such as a woodchip paddock can all help. Late cut hay that feels coarse and stalky is likely to be higher fibre and therefore lower calorie compared to one that is soft and leafy and is the idea choice for a good doer. If you don’t have the benefit of being able to choose your forage then replacing up to a third of the hay ration with straw is a great way to dilute the calories the forage is providing. This wouldn’t be suitable for horses with dental issues or those with a history of impaction colic but it is another useful way to reduce calorie intake whilst encouraging chew time for many horses and ponies.