The right nutrition is essential to keep horses happy and healthy and good nutrition revolves around including the correct levels of nutrients. There are six so-called ‘essential’ nutrients in the horse’s diet

• Carbohydrates
• Fats
• Protein
• Vitamins
• Minerals
• Water

Water is easily the most essential nutrient and despite its importance, water is frequently overlooked when considering a horse’s dietary needs and is often referred to as the ‘forgotten nutrient’, when it should be the main one.

During hot weather the horse’s water intake will increase significantly and it’s vital for their health and well-being that we as their owners and carers ensure that their water intake needs are met.

Lisa Elliott, MSc – Equine Nutrition Solutions shares some insights into just why water is so important, what influences daily intake, and ways to maximise intake through a hot spell of weather and throughout the summer.

Why is water so important?

Put simply the horse can’t survive without water. They can survive for up to ninety days without food but without water they can only survive seven days. In mature horses, total body water comprises 61-72% of bodyweight (BW) and in foals it’s estimated at 66-84% BW, demonstrating just how important water is within the body.

Water is a universal solvent and is directly or indirectly involved with virtually every physiological process essential to life, including circulation, digestion, lymphatic system, excretion (urine, faeces, tears, and mucus), and thermoregulation. Full water hydration is, therefore, vital for optimal body function, and if a horse becomes even a little dehydrated, body function becomes compromised. Dehydration is a serious condition which can be potentially life-threatening so it’s essential to make sure your horse is getting enough water to meet their needs. You can check if your horse is dehydrated by carrying out a simple skin pinch test.

Meeting Water Requirements

To meet water requirements within the body, an optimum water balance must be reached. Water balance can be defined as the equilibrium between water input and water output. Water input comes from drinking water, feed, and metabolic processes. All feeds contain water, and the water content depends on the source of that feed. Hay and cereal based feeds typically contain only around 10-15% moisture so contribute very little to the water input but haylage (32-45% moisture) can supply about 25% of water input and fresh grass which can typically be 60-80% moisture in spring and summer, can almost satisfy water requirements!

Metabolic water is generated from the metabolism of carbohydrates, fats and proteins and is estimated to contribute about 11-13% of daily water requirements. Water output or loss is a result of faeces, urine, sweating and respiration. Daily water requirements at maintenance are estimated at about 5L/100Kg bodyweight, but strenuous work in hot conditions can increase this to around 12 – 15L/Kg Bodyweight. This why water intake from feed and drinking should always be sufficient to replace what is lost and meet daily requirements.

Water Intake

Water intake is essential to keep the body functioning well and avoid the detrimental effects of dehydration. Water intake and the amount a horse will drink is influenced by

Body Size/Weight

The horse’s body size and weight influence their water capacity and intake. Larger horses generally have a greater daily water requirement which means a greater water intake than smaller horses or ponies. A large 600kg horse for example, would have a water requirement of around 30 litres – a smaller 300kg pony would be around 15 litres.

Diet

Diet influences water intake through the amount eaten or total dry matter (DM) and the composition of feed. Research has shown that horses fed all forage diets containing a greater DM than mixed diets, drank 26% more water. Horses out on fresh spring grass, however, which is higher in water (60-80%) and lower in DM, meaning they obtain a substantial amount of water from grazing, will typically drink less.

Diets that are higher in fibre, protein, and certain minerals such as sodium and potassium can stimulate the thirst response and increase water intake.

Temperature

As the temperature rises, so does water intake and previous research studies have shown a positive link between ambient temperature and water intake, with one study (Geor er al. 1996) showing a water intake increase of 79% when horses were exercised at high temperatures. In colder temperatures, during winter, however, horses are generally inclined to drink less. This is exasperated in very cold conditions where water is likely to be near freezing, making it much less palatable and decreasing water intake.

Workload/Exercise

A higher workload will mean a greater water intake compared to a lighter workload or maintenance. Moderate work, for example, can increase water intake by about 40% above that of a horse at maintenance. Any exercise will potentially increase water intake so horses should have constant access to water during exercise and it should not be withheld. Although it is a common belief that a hot horse should not have water till it is cool there is no scientific basis to support this.

Age

Foals have a greater water intake for their size than mature horses because their urine is less concentrated meaning fluid losses are greater. Older horses may drink less and this can make them more prone to impaction colic and dehydration. It is important that their water intake needs are sufficient to reduce the risk. Also, in a herd situation sometimes bullying of older horses away from water troughs can also reduce water intake.

Illness/disease

Water intake can be impacted by certain health problems. Chronic kidney disease or diarrhoea, for example, can cause increased water loses which must be replaced and these horses will need a greater intake of water.

Any health condition that decreases feed intake, for example, gastric ulcers, can also decrease water intake. At the other end of the scale, certain metabolic conditions along with PPID (Cushing’s) can promote excessive drinking and greatly increase water intake.

Understanding how water intake is influenced is important and will help you to assess whether your horse is getting enough water and when to encourage increased water intake when needed to help meet their requirements.

Maximising water intake during hot weather

The easiest way to encourage regular drinking is by always providing constant access to fresh, clean, and palatable water but there are some other ways to encourage water consumption.

Provide Salt

Adding salt to your horse’s feed can help stimulate the thirst response and encourage drinking. Alternatively, providing a salt lick can make a significant difference to water intake by actively encouraging your horse to drink.

Mash it up

Providing a hydrating mash in hot weather can be hugely beneficial for increasing your horse’s water intake.

You can make a yummy and nutritious mash for your horse with Coligone Fibre cubes or Coligone Fibre BIO

• 1 part fibre cubes
• 2 parts water
• allow to soak for 20 minutes
• Stir and serve

Mashes like this are an excellent way of getting extra water into your horse and help him stay hydrated.

Water is and should be the primary nutrient for horses when considering their dietary needs. By being aware of what affects water intake, how much your horse is getting, and encouraging regular drinking, you can help ensure your horse stays hydrated and healthy throughout the summer months.

If you have any questions about creating the best diet for your horse and keeping your horse healthy through the right nutrition, please contact Coligone – 0333 0503785/07986 183616 or sales@hbradshaws.co.uk.