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Soak Horse Hay - Ultimate Guide

Soak Horse Hay: The Number 1 Ultimate Guide

In this comprehensive guide, we’ll delve into the ins and outs on how to soak horse hay effectively. We will explore the benefits and the problems, both known and unknown of soaking hay.

We will provide you with all the necessary information and step-by-step instructions to ensure the proper soaking of hay for your beloved equine companion.

By following these guidelines, you will be able to optimise your horse’s nutrition and overall well-being. Get ready to dive into the ultimate guide on how to soak horse hay.

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Why soak horse hay?

Most owners soak horse hay for one of three reasons:

  • Reduce non-structural carbohydrates for horses and ponies prone to laminitis or Polysaccharide Storage Myopathy (PSSM)
  • Reduce dustiness for horses and ponies prone to chronic Obstructive Pulmonary Disease (COPD)
  • Reduce potassium levels for horses affected by Hyperkalemic Periodic Paralysis (HYPP)

Hay analysis can determine the NSC (non-structural carbohydrates) value of your horse’s hay. NSC in hay refers to the carbohydrates present within the plant cell, excluding the cell wall.

Nonstructural carbohydrates (NSC) in forage are made up of water-soluble carbohydrates (WSC), ethanol-soluble carbohydrates (ESC) and starch. Starch refers to long-chain polymers of glucose molecules, while ESC consists of simple sugars like fructose and glucose.

WSC primarily comprises fructans and pectins. The terms water-soluble and ethanol-soluble indicate the processing of hay fibre in the lab to measure these fractions.

Soaking hay with water not only removes WSC but also reduces ESC content. This is why soaking hay is helpful for horses and ponies prone to weight gain and laminitis because insulin levels can be influenced by ESC content along with starch levels.

Enzymes in the horse’s digestive system break down non-structural carbohydrates, specifically starch and ESC fractions, which are then absorbed in the foregut. It is this process which can rapidly elevate blood sugar levels and trigger an increase in insulin levels which it is why it is these fractions of carbohydrate that are important to know for horses and ponies prone to laminitis.

It is spikes in insulin levels that are associated with both weight gain and the development of laminitis. Insulin spikes also affect PSSM horses. This is why soaking hay can be effective because it washes out the fractions which cause an insulin rise.

When you soak horse hay what are you trying to get rid of for laminitis prone horses?

There are all these terms …. Nonstructural Carbohydrates (NSC), Non-Fiber Carbohydrates (NFC), Ethanol Soluble Carbohydrates (ESC), Water Soluble Carbohydrates (WSC) but what it all really comes down to is hydrolyzable carbohydrates for laminitis prone horses.  
  
Hydrolyzable carbohydrates (HC) are defined as those digestible in the small intestine. Some microbial fermentation occurs in the small intestine but much less than in the hindgut, so hydrolyzable carbohydrates will primarily be absorbed intact.

Insulin levels in horses can be influenced primarily by HC which are simple sugars (ESC fraction) and starch. Starch is digested entirely to glucose. Simple monosaccharide sugars like glucose and fructose are absorbed intact.

Disaccharide sugars like sucrose (table sugar) and lactose (milk sugar), and the trisaccharide, trehalose are broken down into monosaccharides by enzymes present at the brush border of the small intestinal cells, and then absorbed. These are the HC and the only components that increase blood glucose and, therefore, insulin.

To maintain the health of ‘at-risk’ horses, it’s recommended to keep the combined percentage of HC, which are measured on analysis, as the two components (ESC + Starch), below 10%. When the combined percentage is above 10% (above 7% for very sensitive horses) this is when it is useful to soak horse hay before feeding to laminitic horses and ponies.

When calculating nonstructural carbohydrates (NSC), which includes ESC, starch, and fructan, it’s crucial not to overlook the fact that fructan is not an HC. Relying solely on NSC may lead to the unintended neglect of hays that are actually safe for consumption and or very long soaking times to remove carbohydrates that are not a problem.

Soak horse hay reasearch

What about fructans and soaking hay?

It’s important to understand that fructan, often mistakenly labeled as a sugar, is actually a complex carbohydrate similar to fiber, and it cannot be digested by the horse’s enzymes.

Horse owners are led to believe that fructans will affect laminitis prone horses but Borer et al 2012 observed no insulin response to fructan in ponies with or without a history of laminitis.

Crawford et al 2007 administered a moderate fructan dose to both healthy and laminitis-prone ponies and examined the impact on faecal pH and fermentation products. Although pH and fermentation products did change, these alterations were not reflected in blood levels, indicating no absorption. Additionally, no discernible differences in the observed changes were found between normal and laminitis-prone ponies.

Fructan is not significant and instructions to rely on NSC alone is likely to lead to overlooking safe hay options and hay soaking which is too long or unnecessary. What should always be looked at is the combined simple sugar (ESC fraction on analysis) and starch levels in the hay. This is what should inform you whether to soak horse hay.

Can you wash the starch out when you soak horse hay?

No, starch has very limited water-solubility. However, if the combined level of both the simple sugars and the starch is above 10% then if you soak horse hay the simple sugars will lower and make the combined amount safe or safer.

One thing to be aware of with starch is that high levels in hay, 2% or more will double the effect of ESC. This means that whatever starch level you have of 2% or over will have a big impact on insulin levels. For example, a starch level of 2% will represent an ESC level of 4%, and a starch level of 2.5 % will represent an ESC level of 5%. When looking at analysis then, and determining hay or haylage suitability to feed to laminitis prone horses, the starch level must be considered.

The Forageplus database of many thousands of nutritional hay analyses from the UK and Europe shows that starch levels in some hays can be impacting considerably on raising insulin levels in susceptible horses.

What are the benefits of soaking horse hay?

  • Horses with metabolic conditions can benefit from lowered simple sugar levels which affect insulin levels.
  • Soaked hay can lower sensitivity to mould, dust and fungal spores in horses with respiratory problems.
  • Soaking hay to reduce its simple sugar content may be advantageous for overweight horses on calorie-restricted diets. However, there are downsides to this weight-reduction strategy which will be discussed below.
  • Soaking hay decreases its digestible energy, thus allowing for increased feeding quantities due to its lower energy density. Increased levels of fibre in the diet can help prevent ulcers and the development of stereotypical behaviours in horses, but again, there are downsides to this strategy which will be discussed below.

What are the drawbacks when horse owners soak horse hay?

  • The hay will lose valuable water-soluble nutrients which may be hard to replace. Diminished nutritional value may impact horses in many negative ways. This study recommended that horse owners must consider the drop in nutrient density when adjusting feed for horses.
  • Extended soaking periods can decrease the hay’s palatability, affecting the horse’s willingness to consume it.
  • Soaking hay requires significant water resources and produces effluent.
  • When you soak hay it is a time-consuming and heavy job.
  • The loss of simple sugars during soaking can be at varying levels, depending on the maturity and type of hay. This makes it challenging to determine suitable levels for laminitic horses or ponies unless forage analysis is used.
  • Depending on the time of year and seasonal temperature there can be increased bacterial count if you soak horse hay. Soaking hay can encourage the growth of microbes and contamination, posing potential harm to horses.
  • Soaking hay can be very difficult if winter weather drops below freezing.
  • All horses need sugar in their diets, lowering the sugar content in the diet when you soak horse hay can create a situation where not enough sugar is available. In this situation, horses and ponies will become lethargic and very tired.
  • Horse hay which is soaked for a long period of time (hours) in the same water will sit in a toxic soup. In a study of five types of hay, researchers found that bacterial contamination increased by 50% in hay soaked for 10 minutes and 500% if soaked for 9 hours. 

When should you soak horse horse hay?

It is good to soak horse hay if you are unable to carry out nutritional analysis of hay and the horse has laminitis or is laminitis prone, but you should soak it in a particular way to minimise the loss of valuable and often hard-to-replace water-soluble nutrients.

If nutritional forage analysis shows that the hay is above 10% combined ESC and starch, as fed, then soaking should be carried out.

When should you NOT soak horse hay?

Due to the fact that soaking hay reduces nutrient values, Forageplus strongly recommends that soaking should not be constantly carried out for weight loss purposes without reference to both a nutritional and mineral analysis.

Long-term soaking of hay and calorie restriction will result in malnutrition which is highly likely, over time, to result in a host of health issues; skin, digestion, tendon, ligaments, hoof quality and abscessing, lethargy and failure to thrive.

Short-term soaking is more acceptable but the sugar levels could still be lowered below a level that is healthy. There is a lack of research papers showing what happens if you limit carbohydrates too much in the horse’s diet. In this study, they cite 6% as the minimum. As we regularly see sugar levels as low as 6%, after nutritional analysis, then soaking a hay like this will lower carbs to a point where horses ‘hit the wall’ when they are asked to do exercise.

What happens when sugar is too low in the horse’s diet?

When there is too little sugar and starch in the diet, the body may not have enough glucose, which is the primary energy source for cells. This can lead to a state of energy deficiency.

In response to low glucose levels, the body will start to break down stored glycogen in the liver and muscles to provide glucose. However, these glycogen stores are limited and can be depleted within a day or two.

When the glycogen sources are depleted the horse’s body recognises that it has reached its physiological limit. The brain then starts sending signals to the muscles to limit their function and avoid muscle damage. The body will start to break down fats and proteins to produce glucose. This process is less efficient and can lead to weight loss and muscle wasting over time.

In horses, a diet low in sugar and starch may not be able to keep up with the energy losses, especially after exercise. This can lead to signs of insufficient glycogen, such as the inability to continue performing beyond a certain distance/time duration with slow work and inability to meet speed targets with faster work. Muscles are likely to fatigue and become sore.

In addition, a diet highly restricted in sugar and starch may also be restricted or unbalanced in protein, vitamins, and minerals, which can lead to nutritional deficiencies.

If horses are repeatedly asked to carry out physical exertion under conditions where glycogen reserves are constantly depleted then this leads to fatigue and stress. Stress from long bouts of intense physical exercise triggers the secretion of cortisol. This type of nutritional stress can aggravate existing health issues, and it can even increase physical pain within the body.

Therefore, while it’s important to control sugar and starch levels in the diet, especially for horses with metabolic syndrome, a diet too low in these nutrients can have very negative effects.

When should you steam hay?

Some owners will use a hay steamer to reduce dust and allergy-causing particles. This is an effective way of making hay safe to feed to horses with COPD but it does not reduce the simple sugars in the hay. The only way to reduce simple sugars is to rinse and soak the hay.

Research shows that soaking hay for 30 minutes reduces the number of respirable particles by approximately 90%. Soaking hay dampens these particles to reduce the amount breathed in by your horse, but does not destroy them in the same manner that steaming does.

Are there drawbacks to steaming hay for horses?

A group of German researchers conducted a study to evaluate the effect of high-temperature steaming on protein and amino acid levels.

This study steamed hay for an hour and found that heat damaged the protein availability in the hay. The digestibility of proteins and their key amino acids dropped by as much as 56% as a result of heat damage.

Soaking horse hay is an alternative method to steaming, as it effectively removes tiny particles that can be breathed in. While steaming is the only method that kills organisms, the main concern here is not infections but rather sensitivity to fungal or bacterial particles that are small enough to be inhaled. Additionally, fine dust can cause irritation. Washing the hay resolves this issue.

In our opinion a thorough rinsing or dunking of hay for 10 to 15 minutes, with agitation before and after soaking, is just as effective in settling small particulate matter. If you do steam then you will have to replace all the damaged protein and as, here in the UK, it is already hard to provide the minimum levels of protein, due to low levels in hay, then we would suggest it is best NOT to steam hay without replacing the additional lost protein.

Soak horse hay or use a horse hay ball

Is soaking hay good for weight loss?

Soaking hay is often recommended for weight loss. There is no doubt that sugars and therefore calories are reduced by a soak of horse hay but we find that long term use of this approach for weight loss often results in a decline in horse health and performance.

When hay is poor in nutrients this creates more problems with the metabolic system, so if you don’t have to soak then it is best not to wash water-soluble vitamins and minerals down the drain. 

A much better and more effective approach for horse weight loss is to know, by testing, how many calories (megajoules) there are in the hay your horse eats and feed a measured amount, spread out, to keep digestive health.

Controlling calories is crucial.  There are many horses who are ‘good doer’ types where people just do not accept that too many calories means weight gain.  These horses cannot be fed adlib hay.  They have to be fed a measured amount and this, controlled and fed to them over a 24-hour period, in small holed hay nets which slow down eating. 

The goal is to feed in a way that doesn’t cause an exaggerated insulin response not necessarily to eliminate all simple carbohydrates. Limiting the meal size of hay below 10% combined ESC sugar and starch is preferable, rather than soaking blindly for long periods of time and hoping for the best.

You should aim to slow down consumption with double netting, small holes and or muzzles, and you can easily facilitate digestive health at the same time as keeping the water-soluble nutrients in the hay and keeping the calories controlled. Nibbleze or Trickle Nets are effective although some horses will need these double netting.

A nutritional analysis of hay will give the amount of megajoules (MJ) in a kilogram of hay. This figure can then be used to work out how much hay to feed for slow but safe weight loss. Safe weight loss is that which happens slowly and provides enough fibre for the digestive system to be healthy.

The beauty of nutritional analysis is that it also gives information about how much protein hay contains, the calories (DE) and the simple sugar and starch levels. These figures enable the basics of enough protein, low enough sugar and starch and the right number of calories to be determined for the horse’s body weight, workload and age. This is the most effective weight loss strategy because it covers all the critical health basics for a horse. We suggest you don’t guess, you test.

What is lost when you soak horse hay?

We have already discussed the loss of simple sugars when you soak horse hay but soaking hay reduces levels of several other important nutrients.

In this research study, a considerable loss of sodium (Na), potassium (K), phosphorus (P), magnesium (Mg), and calcium (Ca) was reported. Soaking for a longer period, at least up to 12 hours, resulted in higher losses of Mg and further losses in Na, K, and P.

This study found a soak of horse hay caused the leaching of various nutrients, including phosphorus, potassium, magnesium, manganese, zinc, copper, and iron. The study revealed that soaking hay for as little as 15 minutes significantly reduced levels of trace minerals, crude protein, and amino acids. Nutrient and energy losses were appreciable after 15 minutes of soaking, and longer soaking durations did not enhance the washout effect.

How are the carbohydrate fractions in horse hay affected by soaking?

The factors which affect the reduction of carbohydrates when you soak horse hay include:

  • Length of soaking time
  • Temperature of the water used
  • Maturity and species in the hay

Research shows that carbohydrate reductions in hay, due to soaking, are highly variable. In this study, hay was soaked at 8oC for 16 hours.  The researchers looked at the WSC content of the hay before and after soaking. Prior to soaking, WSC content ranged from 123 to 230 g/kg dry matter.

After soaking, the hay lost an average of 27% of WSC content.  However, total reductions in the hay tested ranged from 6 to 54 percent of WSC which is a massive variability.

What is very important to understand about the variability of losses in hay is that different species and maturitity of grasses will lose nutrients more easily than others. You cannot tell just by looking at hay whether it will lose nutrients (minerals and carbohydrates) easily or not. This is where it is vitally important to test and not guess. Depending upon the losses, you could be looking at the difference between enough nutrition and insufficiency, or even deficiency that will lead to malnutrition. When testing is available it does not make health sense to guess.

A different study looked at soaking in warmer water and comparing agitation with a static soak of horse hay. The hay was soaked at 16oC for 16 hours. The average loss of carbohydrates in the horse hay at 16oC was 46%. Agitation, at this same temperature, showed a slightly improved loss of the WSC content, at 49%.

  • Fructan: 24 percent
  • Fructose: 41 percent
  • Sucrose: 45 percent
  • Glucose: 56 percent

The average percentage losses of the different carbohydrates in the hay were:

Carbohydrate FractionLosses 16CLosses 16C plus agitiation
Fructan37%39%
Sucrose86%91%
Glucose85%75%
Fructose52%54%

What is the right amount of carbohydrate in horse diets?

When horses have a diet low in carbohydrates it can have various effects depending on their individual metabolic needs and level of exercise. Some horses, especially those doing less strenuous work, may be just fine with lower levels of glycogen in their muscles. However, signs of insufficient glycogen can include the inability to continue performing beyond a certain distance/time duration with slow work and inability to meet speed targets with faster work.

Glycogen is a storage form of glucose in the muscle and other tissues, like the liver. It is normal, and desirable, to find glycogen in muscle. It provides a stored source of energy for exercise. Glycogen is actually the limiting factor for exercise. When it is gone, or severely depleted, performance suffers.

It is not desirable to lower simple sugars too much in the daily diet. If you soak a hay that is already low in carbohydrate you may well find you have lowered it below health-sustaining levels because glycogen will become severely depleted in the body.

All horses need above 6% combined simple sugar (ESC) and starch in their diet but for an EMS horse this should also be kept below 10%.  Horses without EMS, even good doers, and especially those in work will often need above 10% sugar and starch if they are exercising regularly and doing any fast or sustained work.

What problems does soaking horse hay cause when carbohydrates are too low?

In some cases, horses on extremely low carbohydrate diets, when put back to work can develop hypoglycemia with prolonged or intense exercise. These horses are described as ‘hitting the wall’ and may also exhibit pronounced tripping and stumbling that can be mistaken for neurological disease. They may well exhibit extreme lethargy and tenderness of muscles.

As soaking hay always lowers crucial carbohydrates then it should be done with caution and only when certain the hay soak will not cause carbohydrate levels to fall below what is critical for whole horse health. This is a must for horses in any kind of exercise, even light work.

Glycogen is crucial for horse performance and energy levels. When muscle is being exercised, it relies very heavily on glucose stored in the form of glycogen. Circulating glucose is also used but is not enough to support exercise. As blood sugar enters the exercising muscle, it is replaced by the liver from the breakdown of glycogen. When exercise is not too intense, fat can provide some of the substrate for aerobic generation of energy, but glycogen is always going to be burned to some degree.

Where hay fed to horses is below 10% in simple sugars and starch then care should be taken to replace glycogen losses with a targeted bucket feed after work.  If this is not done, then glycemic reserves will be lowered, and performance and health will be affected.

Forageplus research on soaking horse hay

As Forageplus are leaders in the UK in the analysis of horse forage, and matching feed suggestions to this analysis, we undertook our own research to collect data on nutrient losses after horse hay soaking. This data would equip us to be able to support our customers and their horses more effectively so that our feed suggestions were able to support critical horse health. We could also see if we could replicate results from existing studies into soaking hay.

We soaked to look at how soaking lowered the simple sugars, and minerals, whether protein levels were affected, and how many calories (megajoules) were lost as a result of different soaking length times. Amounts are reported as 100% dry matter.

Research to look at major and trace minerals lost in soaked horse hay

A first hay sample was tested to look at mineral losses after a hay soak. The same sample was split and soaked in a measured amount of cold water with a temperature of 14oC for:

  1. An unsoaked sample
  2. A soak of 2 hours in cold water
  3. A soak of 8 hours in cold water

Each sample weighed 80 grams and was agitated before leaving to soak and again at the end of the soak. Each soaked sample was dried at 50 degrees C in a conventional fan oven with the door slightly open before sending for analysis. chemistry, using a UKAS and GMP+ accredited laboratory to satisfy quality management and assurance schemes, was used to test for minerals in the hay.

What major minerals were lost when soaking horse hay?

The Forageplus results aligned with other published research that looked at soaking horse hay, showing that the significant losses were with the major minerals. The following graph shows the extent of these major mineral losses after soaking hay.

A bar chart showing the Major Mineral Loss from soaking horse hay for different lengths of time.

The table below shows the same data as the percentage loss. The greatest loss when you soak horse hay was seen in the chloride levels which lost 84% of the content over an 8-hour soak. It is concerning how all the major minerals, apart from calcium show losses of 50% or more when hay is soaked for 8 hours or more. The implications for this on horse health are extensive.

Percentage Major Mineral Loss after Soaking Horse Hay

MineralLoss after 2 hour soakLoss after 8 hour soak
Phosphorous44%56%
Magnesium31.25%50%
Sodium71.5%81%
Potassium59%72%
Chloride82%84%
Calcium1.85%3.7%

How does mineral loss after soaking hay affect horses?

Any horse owner carrying out hay soaking should be aware that a horse hay soak reduces certain minerals in the hay by as much as 80%. Because of this horse owners, and professionals recommending testing, need to understand that meticulous attention must be paid to replacing these lost minerals as all of them are critical to long-term horse health.

Magnesium losses when soaking hay can contribute to muscle and nervous system challenges as poor levels often exacerbate PSSM-like symptoms and irritable behaviour.

Sodium losses will lower a mineral which is often already low in forage. Poor sodium in the diet creates lethargy and tight painful muscles. Low levels depress thirst which can slow digestion creating colic episodes.

Lowering phosphorous levels following soaking of hay can affect bone strength, how the body uses carbohydrates and fats, and uses protein for the growth, maintenance, and repair of cells and tissues.

Potassium, although lowered considerably when carrying out a soak of horse hay, is at such high levels already in forage that problems are not seen until there is a deficit due to sweat losses not being replaced. Horses then on soaked hay in moderate to heavy exercise, may need to be supplemented extra to avoid muscle tremors, cardiac arrhythmias, and weakness.

Chloride is washed out at high levels when hay is soaked for long periods. Deficiency in this electrolyte mineral can cause gastric reflux, lethargy, muscle tremors and colic. Both sodium and chloride deficiency can be linked to tying up in horses.

What trace minerals were lost when soaking horse hay?

Trace minerals were not significantly affected in the Forageplus hay soaking study, although two separate labs showed a significant rise in iron levels in the two-hour soak, which then lowered slightly during the 8-hour soak. More research needs to be carried out to see if this is a consistent finding and to investigate why this happens.

Forageplus research to look at nutritional elements lost in soaked horse hay

Two hays were tested to look at losses of nutritional elements. We wanted to look at the correlation with published studies. The two samples of hay were split and soaked to look at protein losses, reduction of digestible energy (DE) as megajoules per kilogram, and carbohydrate losses measured as WSC (water soluble carbohydrates) ESC (ethanol soluble carbohydrates) and starch.

Each sample weighed 80 grams and was agitated before leaving to soak and again at the end of the soak. Wet chemistry, using an A2LA laboratory, with recognised international standard ISO/IEC 17025 accreditation to satisfy quality management and assurance schemes, was used to test the nutritional elements in the hay. Each soaked sample was dried at 50 degrees C in a conventional fan oven with the door slightly open before sending for analysis.

Forageplus Horse Hay Soak Test One

Hay sample one was a meadow hay and was soaked in a measured amount of cold water (14oC) and hot water (40oC) in the following way:

  1. Unsoaked sample
  2. A soak of 1 hour in cold water
  3. A soak of 2 hours in cold water
  4. A soak of 8 hours in cold water
  5. A soak of 15 minutes in hot water

How much was DE and carbohydrate fractions lowered in Forageplus soak horse hay test one?

Soak TimeWSC %ESC %Starch %Combined ESC and Starch % DE as MJ/Kg
Unsoaked11.38.60.69.28.00
1 hour Cold Water11.068.40.697.6
2 hour Cold Water9.27.60.68.27.5
8 hour Cold Water3.82.60.63.25.7
15 minute Hot Water 11.28.50.69.17.9

Forageplus Horse Hay Soak Test Two

Hay sample two was also a meadow hay and was soaked in a measured amount of cold water (14oC) in the following way:

  1. Unsoaked sample
  2. A soak of 2 hours in cold water
  3. A soak of 8 hours in cold water

How much were DE and carbohydrate fractions lowered in Forageplus soak horse hay test two?

Soak TimeWSC %ESC %Starch %Combined ESC and Starch %DE as MJ/Kg
Unsoaked14.98.61.29.88.38
2 Hour Soak11.03.91.157.5
8 Hour Soak8.43.20.63.77.2

How was protein affected in Forageplus soak horse hay tests?

The protein level was not affected by soaking horse hay in any of the samples we carried out. This has been found to be the case in this study.

Forageplus Hay Soak Test Conclusion

What is very important to notice is that both these hays did not need to be soaked unless the horse was a severe and very sensitive laminitic. The carbohydrate levels fell below 10% combined ESC and starch before soaking, so feeding a measured amount, for both digestive health and weight maintenance, in slow feeder trickle nets would be a better option than soaking and losing high amounts of water-soluble nutrients.

The other aspect to notice is that soaking for 8 hours lowered the carbohydrate levels so much in both hay soak samples that carbohydrate levels in the diet would be far too low to sustain either health or energy in a horse fed this hay, soaked, as the greatest proportion of the diet. As discussed above soaking hay so the carbohydrate levels are below 6% will not be beneficial for any horse or pony in the long term. This aspect is often overlooked by both vets and horse owners who advise or carry out soaking for long periods of time that can amount to as much as 16 hours.

Soak horse hay or use measured hay

What is the best way to soak horse hay to reduce nutrient loss?

The correct approach to soak horse hay is to soak for no more than 1 hour at a time if using cold water. Soaking for more time than this in the same water puts the hay in a toxic soup and has been shown to cause a hygiene issue in hot weather and drive iron into the hay and raise the level. Lowering simple sugars and iron levels in horses prone to laminitis is a key strategy in lowering the incidence of laminitis to the ideal none.

You should rinse and soak horse hay in a particular way to limit the leaching of both minerals and protein.  Hay soaked for long periods can become extremely deficient in all water-soluble vitamins and minerals.  These vitamins and minerals are vital for metabolic and whole horse health and can be almost impossible to supplement at the levels leached from hay soaked for long periods of time.

It is best to see the soaking of hay like the rinsing of clothes when washing them with detergent.  To reduce the amount of soap in the clothes you need to use a large volume of water, agitate the clothes and change the water frequently.  This is the same with lowering sugar in hay, you should try to use one of the following systems:

How to soak horse hay in cold water

Fill a large container roughly double the size of the hay net to be soaked with cold water.  Place the hay in the water, submerge and agitate for a few minutes. Leave to soak for around an hour then agitate again before discarding the water.

This should be sufficient to reduce most hays below a combined level of 10% ESC sugar and starch. If your horse is actively laminitic and not responding to a one hour soak, (response is where laminitis improves) and you are unable to test the hay, then you can repeat the submerging, with different water, agitating and soaking for another hour.  This can be repeated one more time, again with different water, then the hay can be drained out of direct sunlight.  This method although time-consuming is preferable to leaving the hay sitting in the same water for many hours.

How to soak horse hay with hot water

Fill a large container roughly double the size of the hay net to be soaked with hot water.  Place the hay in the water, submerge and agitate for a few minutes. Leave to soak for around 15 minutes then agitate again before discarding the water and replacing it with new.  Repeat the submerging, agitating and soaking for another 15 minutes. 

Repeat one more time, then drain the hay.  This method is preferable to leaving the hay sitting in the same water for many hours, using hot water can make the reduction of the sugar in the hay much more effective.  The use of a Gas Shower is very effective for this purpose.

Nets to reduce horse hay soak time

When should you test rather than soak horse hay?

You should always test rather than guess if you can. By testing the hay you are feeding, you can determine its nutritional value to see if the simple sugars and starch are below 10% when combined.  In this scenario, you will not need to soak the hay at all.

A nutritional analysis will also allow you to determine both the calorie and protein levels.  Knowing calorie levels will allow you to feed the correct volume of hay for healthy weight maintenance and maintain good digestive health. Knowing the protein level will allow you to make sure there are adequate levels of protein supplying all the essential amino acids to promote whole horse health.

Our strong advice is to consider carefully before soaks of over two hours are carried out. Veterinary advice should be based on advising horse owners to test the hay first, if they can. Where testing is not possible the advice should not be a blanket soak for long periods, without any consideration of the downsides of such practise.

How to know how much hay to feed for weight maintenance if you can’t test

Most horse owners are unaware of the extent of water-soluble nutrients washed down the drain when they soak horse hay. They may be predominantly soaking hay to reduce the digestible energy (calorific) value of the hay.

They believe, incorrectly, that they have to feed adlib hay and would rather feed hay soaked for long periods of time, adlib, than feed a measured amount. This approach is flawed when you consider that the reduction in calories will not outweigh the potential loss of nutrients which are usually ignored or not even thought about.

As horses have a digestive physiology which is adapted to frequent small meals, management practices should mimic natural feeding behaviour by utilising methods which encourage small mouthfuls and searching behaviour. The goal is to ensure the horse has constant access to forage, but that this forage is measured for calorie control and split throughout the day with the horse never going longer than 4 hours without eating.

Using hay balls with small holes as well as good quality hay nets like the Nibbles blue nets will facilitate this slow, small mouthful, trickle feeding of a measured amount of hay so that a fat horse will lose weight and a good doer maintain a healthy weight but still have access to a good level of nutrients for long term health.

How much hay to feed each day is dependent upon weight, work level and whether you know the calorie content of the hay fed.  A rough guide if you don’t know the calorie content of the hay, through testing, is to feed 2% of body weight to maintain weight or 1.5% of body weight to lose weight. 

If the horse is very overweight another approach is to pick a weight you want the horse to get to and feed 2% of this weight. 

However, you should always be aiming to feed as much forage as possible so choose the method which supplies the greatest volume. Not feeding enough hay will be counterproductive for weight management because the body will go into starvation survival mode but equally soaking hay without thinking about nutrient loss can also mean that the body is so depleted in nutrition that health is affected and a decline over time is likely.

Summary

Reasons for Soaking Horse Hay:

  • Reduce non-structural carbohydrates (NSC) for horses prone to laminitis or Polysaccharide Storage Myopathy (PSSM).
  • Reduce dustiness for horses with Chronic Obstructive Pulmonary Disease (COPD).
  • Reduce potassium levels for horses with Hyperkalemic Periodic Paralysis (HYPP).

Understanding NSC:

  • NSC includes water-soluble carbohydrates (WSC), ethanol-soluble carbohydrates (ESC), and starch.
  • ESC and starch impact insulin levels, which are crucial for laminitic horses.

Digestive Process:

  • Horses break down NSC in the small intestine, raising blood sugar and insulin levels, potentially leading to laminitis.
  • Hydrolyzable carbohydrates (HC) include simple sugars and starch, which significantly affect insulin levels.

Benefits of Soaking Hay:

  • Lowers simple sugar levels, beneficial for horses with metabolic issues.
  • Reduces dust, mould, and fungal spores, aiding respiratory health.
  • Lowers digestible energy, allowing more hay to be fed without weight gain.

Drawbacks of Soaking Hay:

  • Loss of valuable water-soluble nutrients.
  • Reduced palatability.
  • Time-consuming and labor-intensive process.
  • Increased bacterial contamination risk in warm weather.

Optimal Use of Soaking:

  • Beneficial if hay analysis shows high ESC and starch levels.
  • Not recommended for weight loss due to nutrient loss risks.

Fructans and Soaking:

  • Fructans are not hydrolyzable and don’t impact insulin levels.
  • The focus should be on ESC and starch levels rather than NSC alone.

Steaming vs. Soaking:

  • Steaming reduces dust and allergens but doesn’t lower sugar content.
  • Steaming may reduce protein availability.

Nutrient Losses:

  • Soaking can leach essential nutrients like sodium, potassium, and magnesium.
  • Recommendations:
    • Use hay analysis to determine the need for soaking.
    • Consider soaking duration and water temperature to optimize carbohydrate reduction.

In conclusion, soaking hay can be beneficial for specific health conditions in horses, but it must be done carefully to avoid nutrient losses and bacterial contamination.

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