The Keep It Simple Equine Diet

The

“Keep it Simple”

Equine Diet Plan

By The Nude Horse

(Equine Epidemiologist)

Social media feed fads, peer preferences and clever marketing can make selecting a straight forward and effective diet for your horse a difficult one.

Do you ask yourself:

·         Do I need all these additives?

·         Do premixes really meeting all my horse’s need? 

·         Is my feed shed filling and my pocket emptying yet my horse still hasn’t improved?

Some worthy facts to consider:

·         Meeting dietary needs is important

·         Sustaining muscles and electrolytes at rest and in work is essential

·         Providing nutrients for breeding and lactating horses is necessary

·         Minimising sugar intake for overweight and insulin resistant horses is paramount

·         Hoof growth and quality is the foundation of a good horse

·         Managing an itch prone or immunocompromised horses can be achieved

The confusion begins:

·         Fads on Omega 3 from Chia seeds, flaxseed or fish oils - which one is best or is any necessary?

·         Reading articles about Vitamin C from Ascorbic Acid or herbs like Rosehip, again necessary or just a fad?

·         Lecithin for suspected ulcers? True or False?

·         Toxin binders - does my horse even consume toxins? 

·         Pre and or pro-biotic?  Do I need these?

·         My horse is stressed sometimes, is it a behavioural issue or can I help through nutrient balancing?

Are you bombarded with choices of supplements for horses kept on grass - without grass - in work - at rest?

Keeping It Simple--

The basics needs:

·         Roughage – approximately 70 % of the horses feed should be in the form of roughage (hay, pasture or chaff).

·         A salt lick (Himalayan rock salt is a great option as it doesn’t contain any additives). 

·         Water at least 30ltrs a day in cool weather for full size horses and double in hot weather or heavy workloads.

·         Minerals and Vitamins to meet dietary needs

The volume feed needed can be worked out as:

1.7 (% of bodyweight) x 500 (kg horse) = 8.5 kg max feed
                    100
(In this example the horse weighs 500 kg, so it can safely consume up to 8.5 kg of dry feed per day.)

Next work within your budget, if you can afford additional quality feeds stuffs, work out what you can afford and what you actually need.  If constrained in your budget, work out your cheapest roughage option and add a quality mineral and vitamin supplement.   Readers of The Nude Horse voted Flowers Gold as the most comprehensive and absorbable daily mineral and vitamin mix to meet dietary needs.

You can make your own hard feed to carry the mineral supplement with something like copra & lucerne chaff that is low GI (sustained energy and a cool feed), the bonus is you can increase the bulk to gain weight or reduce when grass and forage abounds.  If using a premix, be wary of varying the feed quantities as this will alter the mineral intake.    Choosing to make your own feed blend allows you to take control of the quality and quantity of mineral and vitamin consumed daily and know your ingredients are fresh and mould free.

According to the National Research Guide formulated by combined global research from the very best University studies one can see the necessary daily intake for each age, sex, weight of horse whether in work, breeding or rearing.

Facts:

Protein: Protein is made up chains of amino acids.

Only lysine has been studied in horses and the known daily requirement has been established.  Quality of proteins should be considered above quantity as amino acids need to be utilised in the foregut to contribute to the amino acid pool for tissue synthesis and repair.

Pasture grass delivers approximately 0.92% Lysine/DM.  Lucerne hay supplies 0.83 % Lysine/DM and Soybean meal delivers 3.38 % Lysine/DM.  All feed sources should be factored into daily intake.  

Sugar resistant horses:  Chromium appears to be directly involved in carbohydrate, fat and protein metabolism.  It is especially important for horses with endocrine disorders or metabolic syndromes such as Cushings and Hypothyroidism.  Chromium is integral in the regulation, stabilization, metabolism and absorption of sugars in the blood. 

Feeding the right hay is important for sugar sensitive horses, of note Lucerne hay delivers approximately 12 % NSC (non-structural carbohydrates) compared to oaten hay supplying around 22% NSC.  (https://kppusa.com/tips-and-topics/picking-hay-sugarstarch-sensitive-horses/).

Biotin for hooves assists the outer wall of the hoof to grow faster, fed with organic manganese enables the body to utilise biotin.  Feeding together encourage healthy outer and inner hoof wall growth.  Organic Selenium and Organic Zinc also play key roles in healthy hooves. 

Healthy shiny coat: Predominately organic zinc and organic selenium balanced in their synergies such as with organic copper produce healthier coats.  When dietary needs are adequately met coat colour will deepen and glow.  Bioavailability of nutrients means sourcing a supplement with these hard to absorb minerals in an organic and chelated form. 

Allergy to midge saliva: The problem with allergic reaction begins when incorrect signalling occurs at the cytokine level.  (http://cid.oxfordjournals.org/content/32/1/76.short)

Experimental feed supplements are showing signs of assisting a correct response cytokines to initiate an anti-histamine and heparin defence. 

Horses fed diets enriched with Omega 3 EPA and DHA (fish oil) demonstrated modulation of inflammatory mediators, possibly resulting in a decrease of allergic skin responses. (NRC, Nutrient Requirement for Horses 6th Ed).

Omega 3: When grass abounds the natural balance of Omega 3 to 6 ratio occurs close to 4:1, this is ideal for horses.  When pasture is unavailable, it is recommended by Kentucky Equine Research to supplement 60 ml/day of fish oil. (Pagan, Lawrence, Lennox).

Flaxseed provides a plant based ALA form of Omega 3, however only 5% is able to be converted into the necessary EPA and DHA able to be utilised.

Feeds that are proportionately too high in Omega 6 to Omega 3 are vegetable & seed oils (soybean, cotton seed, sunflower seed, corn, grape seed, rice bran, peanut, sesame oils) Corn oil for example has an omega 6 to omega 3 ratio of about 45:1!  Caution should be exercised with seeds like sunflower, sesame & pumpkin along with grains including corn, oats, wheat, quinoa and rice, not to be missed are legumes like soybean and peanuts that are very high in the Omega 6 fatty acids.

 http://nutritiondata.self.com/foods-000141000000000000000-1w.html?

Vitamin C:  Horses synthesise Vitamin C in their liver from green feeds and thereby supplying additionally in their feeds is deemed unnecessary.  Studies show supplementation of small doses of Vitamin C at the 80 km endurance level may be beneficial.

(https://dl.sciencesocieties.org/publications/jas/abstracts/82/2/0820588)

Lecithin for ulcers: In a  comprehensive study pectin lecithin failed to prevent lesions in the gastric ulcers. (http://onlinelibrary.wiley.com/doi/10.2746/042516402776767268/abstract).

Another comprehensive clinical trial revealed there were no significant differences in the ulcer scores between mares that received lecithin and mares that didn’t. (http://www.repository.up.ac.za/dspace/bitstream/handle/2263/45481/Sanz_Efficacy_2014.pdf?sequence=1&isAllowed=y)

Toxin Binders: Horses exposed to mycotoxins in their feeds (mouldy hay) can benefit from varied forms of toxin binders.  A variety of options include: diatomaceous earth,  zeolite, cellulose, polysaccharides, mannon oglisaccharides, kaolinite & bentonite clay and alumina-silicates.

Toxin Binders are useful as a preventative feed supplement, not a treatment once toxins have been ingested.  Avoiding premixes/pellets may reduce the exposure to potential moulds hidden after processing.

Pro and prebiotics: Dr David Marlin a Scientific and Equine Consultant recommends “It is worth considering feeding a gut balancer type of product to horses under stress, horses prone to colic or laminitis, horses that develop GI upset on medications such as antibiotics, to horses around the time of worming, when changes to diet are made, for poor doers, older horses that lose condition and horses that develop loose droppings”. 

Nervous horses: Supplementing with nutrients that have been demonstrated to reduce symptoms of anxiety and stress hormones, along with supporting normal cognitive functions that assist building the brain’s chemical messengers called neurotransmitters can be beneficial. 

Caution must be exercised not overloading with high quantities of magnesium for example whereby ‘slurred’ behaviours can potentially endanger the safety of you and your horse.  Magnesium can throw off absorption of other vital nutrients.   Look for a balanced blend of amino acids, vitamin B’s (not with Vit B12 in combination as it blocks out the functions of the other B’s), small amounts of magnesium and select beneficial plant extracts.

Mindfulness for Horses 'Beyond Prey & Predator"

Beyond Prey & Predator

 “Mindfulness”

By The Nude Horse

(Equine Epidemiologist)

Understanding the natural position horses have in the complex animal kingdom helps us enter into a very unique partnership with an animal of prey with humans as potential predators.  Horses are in-between fully domesticated ‘pets’ like dogs and cats that live in our homes, yet they are unlike agricultural animals kept for consumption and maintained at arm’s length.  Horses offer a glimpse into the wild world, yet are curious and willing enough to allow us to train and tame them.

To train a flight & fright based animal in a prey/predator relationship requires a handler to be always ‘mindfully in the moment’ when with a horse. 

Horses have been surviving in the wild successfully based on their strong cooperative social structure, so we need to learn how to enter this social structure and provide calmness, fairness, be an intelligent leader to protect them and secure their trust in us enough for their perceived survival.  Becoming these things to your horse allows them to seek us for comfort in situations that would otherwise be fearful and trigger the flight & fright responses –these unwelcomed responses are often exhibited at shows, loading onto floats, riding in new locations and tackling new tasks asked from the handler.

Horses live in the moment, are large, powerful and thus potentially dangerous.  These days many horse trainers are becoming aware of the importance of being ‘mindful’.  They do exercises based on breathing, relaxation and body awareness.  They are becoming non-confrontational in their methods (coined ‘natural horsemanship’ by some) working with an understanding of the horse ethology, as opposed to old school methods of domination.

How is ‘mindfulness’ achieved?

Try adjusting your breathing to the pace of your horse; switch off the world around you (especially your mobile phone).  Aim to connect with your horse with your eyes and your breath, look with him, not at him; a predator will stare at their prey.

Spending time with your horse when unable to concentrate can be called having a ‘monkey mind’.  Without concentration you begin to let wandering and disjointed thoughts occupy your mind, perhaps rushing through activities, being unaware of the tension the horse or yourself may be feeling.  Your horse may likely respond inappropriately, basing their decisions on past experiences, fear or even past trauma (returning to a state of flight or fright), they are unable to tap into your comfort for reassurance.

By contrast, have you seen a ‘mindful’ person enter the paddock and their horse comes up eagerly to greet them?  There is a visible connection between both the horse’s eye and that of their handler; they both exude calmness, a relaxed state of mind a mutual trust between them. 

One might start with spending time learning to keep their attention focussed over a sustained period of time through relaxation techniques, this in turn serves to develop concentration, calmness, flexibility in controlling ones thoughts and ultimately leads to a state of being able to be ‘connected or mindful’  to the moment.

Entering the paddock with no purpose other than to sit and observe or play with your horse, allows new skills sets to develop (no halters or leads just a carrot or apple).  Try to renew the relationship through fresh eyes. Allow your horse to see you as a friend rather than a ‘work’ only companion.  Play breeds curiosity – a behaviour sadly ‘trained out’ of many horses, they switch off and become disconnected. 

It makes sense that awareness of our body language and the capacity to monitor one’s behaviours and emotions is necessary to enable this unique prey/predator partnership to flourish.

An equine dentist says “I used to be focused on getting as many horses in a barn done as I could.  Now I am focused on getting as many horses as possible mindful, relaxed and telling me what they need.    

I want the horse to trust and to like me.”  He further states that he could “feel” the horse’s mouth if he just slowed down and took time to be present with them.

When trying to work mindfully with a horse it’s helpful to have a clear schedule.  In other word don’t work your horse when you have to rush or are mentally or emotionally distracted.  This breaks down the mindful partnership and the horse resorts to its natural flight or fight responses.

The same goes for not insisting on working your horse when he/she is not mentally or emotionally fit to do so.  Like humans they can be affected by stress, hormones, herd dynamic changes and wellness issues.   Often the hardest but most important thing you can do it ‘walk away’ calmly and try again another time or day.

Working mindfully with your horse can start with these simple steps created by B.S., M.A. Mary Ann C. Simonds in her article “Mindfulness With Horses”

·         Look “with” not “at” horses (predators lock eyes on their prey). 

·         Empty your mind and centre your mind to be present. 

·         Synchronize your breath with your horse’s breath.

·         Use calming signals such as eye blinking to connect with your horse.

·         Slow your brain wave down from Beta to Alpha frequencies. 

·         Turn off your cell phone and bring your attention into the moment.

·         Spend time just “being” with your horse, like eating, sleeping and play.

·         Use music to relax and connect you and your horse while riding.

·         Be happy and friendly when in your horse’s presence. 

·         Spend time helping your horse feel good and release tension through hands-on massage.

·         Use relaxation techniques such as aromatherapy, breathing, flower essences for you and your horse.*

*http://holistichorse.com/in-the-field/minfulness-with-horses/

Is there reason to believe being mindful makes any difference?

Two interesting cases studies conducted with young person’s considered at risk due to their psychosocial disadvantages and backgrounds demonstrate how practising ‘mindfulness’ enabled a difficult situation to be corrected in both cases, with the horse’s acceptance.

“Frey’s therapist had relayed Freya would often put herself at risk with her peers and engage in risky behaviours outside the residential home.  Once up on the mare named Ruby however, Frey’s distracted behaviour appeared to wane a little and she became quieter in her body language and manner, seeming to suddenly realise she was perhaps vulnerable on top of the horse.  This appeared to enable her to listen to and take instruction more readily and we took some opportunity to introduce her to some ‘invisible riding’ techniques.  In the round pen we initially led Freya around on Ruby, the mare seemed to understand that she needed to remain extra attentive and alert today, perhaps picking up on Frey’s emotional and physical state.  We started off with some simple stretching exercises in order to help Freya find her balance, tune in to the different parts of her body and gain some more confidence, as well as being fun.

Next we introduced some simple ‘body scan’ exercises where Freya concentrated on each part of her body in turn, starting with relaxing her feet, moving up her body until she relaxed her shoulders and neck.  In order to make this more fun and engaging I demonstrated these walking next to Freya, who copied the exercises riding on Ruby’s back.  Once Freya had found her balance and was more relaxed we suggested she closed her eyes and ride Ruby with her eyes shut in order to really tune into Ruby’s movement.  This is not as easy as it may appear but it is a really useful exercise for refining balance and for following the movement of the horse.  Together we demonstrated to Freya how she could slow her breathing down, and breathe in and out in order to influence Ruby’s pace, and learn how to bring her to a halt and to walk on again just by the smallest body movement and breathing.  This exercise takes a lot of sustained concentration and body awareness, together with real intention; it will not work unless you are completely committed and mindfully embodied.  After a few attempts we knew Freya began to get a sense of this feeling as she gained more ability in co-ordinating her body language together with her breathing and concentration.  In turn Frey’s confidence in her newly found body awareness grew and Ruby responded accordingly, causing Frey to exclaim “look she slows down when I’m just thinking it now”.  Later as we finished the session Freya stretched down from Ruby’s back to hug her around the neck beaming it’s like she can read my mind”.”

The second one is “Cinderella approached Duchess in a rather dominant, almost aggressive manner which caused the mare to walk purposefully away from her, refusing to be caught.  Cinderella immediately became angry and frustrated walking off throwing the head collar down exclaiming “stubborn cow”.  I sat down next to her and to her surprise it seemed I praised her for her actions telling her that sitting down and not chasing Duchess was in fact a very good strategy and one of the tactics I may try with a horse who didn’t want to be caught.  I suggested we sit in the field and relax for awhile and try to just observe Duchess and the horses without necessarily trying to catch them, but at the same time bring some awareness as to how she felt Duchess may be feeling. After sitting quietly for quite a long time with only the sounds of birds and the wind in the trees in the background and with Cinderella appearing to be ignoring me she finally said ‘she probably doesn’t want to leave the others and suppose she doesn’t know me yet”.  I asked Cinderella what different approaches may help Duchess to want to be caught and she replied “well probably getting to know me a bit more first as she knows she can trust me.”  We followed this with a short discussion about horse’s body language and whether Cinderella could see if there were any different approaches she could try to help Duchess learn to trust her.  With this Cinderella agreed to try approaching Duchess together with me in a slower more controlled and less aggressive manner and did then succeed in carefully putting the head collar on.  The other mare Ruby then followed us into the yard where Cinderella put the head collar on her too without a problem, her body language reflecting a much more gentle approach towards the horses who responded accordingly.”#

#www.psychosocial.com/IJPR_17/Horses_and_Mindfulness_Burgon.html

What if still your horse is still behaving nervously and seems ill tempered after practising ‘mindful’ techniques?  

Some horses may indeed be additionally suffering from dietary deficiencies, pain or severe trauma.   Ask your vet to rule out any illness, pain or gastric ulcer issues, along with testing for dietary deficiencies.

Supplementing with nutrients that have been demonstrated to reduce symptoms of anxiety and stress hormones, along with supporting normal cognitive functions that assist building the brain’s chemical messengers called neurotransmitters can be beneficial.  Caution must be exercised not overloading with nutrients such as high quantities of magnesium for example whereby ‘slurred’ behaviours can potentially endanger the safety of you and your horse.  Magnesium can throw off absorption of other vital nutrients leading to other health issues.   Look for a balanced blend of amino acids, vitamin B’s (not with Vit B12 in combination as it blocks out the functions of the other B’s), small amounts of magnesium and select beneficial plant extracts.

Getting dietary support right and working on a mindful attitude can lead to better mental performance and a more positive response to stressful situation whether at work or play.

___________________________________________

Excellent follow up reading by horse trainer Mark Rashid is recommended through his many books. Rashid’s philosophy involves understanding the horse’s point of view and solving difficult problems with communication rather than force. His methology emphasises the relationship between horse and the rider as a partnership, in which the horse willingly takes direction from the rider, rather than a dominant rider directing a submissive horse.

Laminitis

EMS is also referred to as Insulin Resistance (IR) and Hyperinsulinemia.  The condition is often triggered by chronic obesity.  Overfeeding of Non-Structural Carbohydrates (NSC), simple sugars and fructans result in increased uptake of glucose by muscles and adipose tissues.  If this happens in chronic levels, these excess sugars will exceed the fat tissues ability to use and store glucose.  This will result in the muscle and adipose (fat) tissues to improperly respond to insulin.  Hyperinsulinemia will result (the body reacts to compensate for the reduced insulin sensitivity and increase its insulin levels even more). Theory suggests high insulin levels alter blood flow and endothelial cell function causing vasoconstriction to the blood vessels and ultimately to the laminae (in the feet).  High insulin may alter the colonic bacteria increase endotoxins causing inflammatory.

See http://www.durangoequine.com/articles/equine-metabolic-syndrome/

How do I know if my horse has laminitis?

Source:  http://www.debenvalleyvet.co.uk/Event.aspx?informationid=5

·         Shifting weight from foot to foot, often quite slowly and subtly.

·         Wanting to walk on the soft, avoiding gravel etc.  May not want to walk or trot.

·         Warm/hot feet.

·         Pronounced digital pulses – your vet can show you where to feel for these.

Signs of distress may be fast breathing, sweating and laying down more than normal.  Noticed perhaps first is the leaning back ‘toe-relieving’ laminitic stance.

Laminitis can develop for a number of reasons, and is currently a hot area of research. However the single most common cause is:

·         Too many calories!

Other predisposing factors and triggers include:

·         Insulin resistance (especially fat ponies)

·         Cushing’s Syndrome

·         Poor shoeing, especially with too much fast work on hard ground / roads (also known as ‘road founder’).

·         Carbohydrate overload/gorging grain

·         Toxaemia or other disease (e.g. liver)

·         Large doses of steroids, or stress

·         Reduction in workload, but not feed volume

 It is now strongly suspected that if a pregnant mare has poorly balanced nutrition – causing obesity - or a lack of vital vitamins and minerals her foal will be predisposed to insulin resistance and be at higher risk of developing laminitis for its whole life.

Management and feeding:

 Severely restricting the volume of food a horse can eat is not ideal because horses are naturally trickle feeders. Long periods without food can result in gastric ulcers.

High risk grazing:

·         Lush grass

·         Hay aftermath

·         Long, dead-looking old grass

·          Frozen grass (Frost affected)

Feeding tips:

Limit the amount of grazing available by increasing the number of horses, reducing the size of the field or using a grazing muzzle.  Mow fields in the summer if they are not used for grazing or hay to prevent them going to seed.  Turn out onto an area which is small enough to be kept grazed short. Suitable grass looks ½ mud and ½ grass.

Don’t be fooled into thinking there’s no grass – usually there’s only no grass because the horse is eating it as fast as it can grow!  If you are mowing your lawn then the grass is growing – if the field looks bare but you are mowing your lawn twice a week then the horses are eating a lot of grass!

Make sure the diet is balanced for vitamins and minerals, especially whilst feeding lots of low calorie fibre, make available “himalayan rock salt, feed a quality pre & pro-biotic (to re-establish gut flora) and feed a toxin binder”. (http://www.hoofnz.org.nz/html/laminitis.html)

Exercise helps reduce insulin resistance, try to ensure your horse gets a minimum of 30 minutes active walking every day.”

Image by Deben Valley Equine Veterinary Clinic

See: http://www.debenvalleyvet.co.uk/Event.aspx?informationid-5

Source: http://www.thelaminitissite.org/articles/equine-metabolic-syndrome-and-insulin-dysregulation

“A common suggestion is to feed a horse 1.5% of its ideal or current bodyweight (based on soaked hay with added minerals).  Do not reduce to less than 1.2% of the horse’s bodyweight.  Severe calorie restriction can worsen insulin resistance.”

Source: http://www.safergrass.org/pdf/sugar_in_hay.pdf

“Soak hay for at least 60 minutes in cold water, or 30 minutes in hot water, drain and feed before mould has a chance to grow. Use fresh water every time, as sugar will build in the water.”

Source: http://www.barehoofcare.com/AB%20articles/Laminitis%20Recovery.pdf

“Whilst ‘bute’ plays a very important role in the early stages of a laminitic episode, it is really only needed for a matter of days, not weeks and definitely not months. Nutritional supplementation is vital to support the body’s efforts at recovery.

A combination of supplements useful during the healing process include concentrating on the ulcerated stomach and damaged digestive system and then liver cleansing.

Facilitate healing through correct trimming. It’s vitally important to remove all weight from the ‘broken’ laminae. That is the only way it is able to begin healing at the coronet. See pictures A, B & C.

Rehab includes soaking in concentrated salt water, cleaning and wrapping in bandages or baby nappies to prevent infection.

A return to soundness comes routinely at three to four months, when the new lamellar attachment reaches ground level at the heels.”

Source: http://naturalhorseworld.com/newsite/laminitis-recovery/

Food Allowed:

“Free choice average quality grass hay plus oaten chaff with quality mineral and vitamin supplements and a small amount of pellets (Hygain Ice recommended) and a few vegetables for variety.

Once the hooves have regained a sound shape, a small amount of grass is allowed daily (1 hour of grazing with a muzzle on
Treatment Summary:
  

·         A natural trim every week for 8 weeks, then every fortnight for the next 6 weeks & now every 3 weeks.

·          Initial bandaging of the front hoof wounds to keep honey in and dirt out until the wounds were healed (3 months).

·         Painkillers to keep spirits up and encourage some movement (gradually phased out after 4 weeks).

·          Confinement away from grass in a large stock yard on soft footing (sawdust & straw then some pea sized gravel was added in wet areas).”

 

Visible Pedal Bone Penetration               

  

Visible blood in the white line   

Bath frequently and bandage  to protect from further infection

Source: http://holistichorse.com/health-care/feeding-the-horse-with-winter-laminitis/

Chinese Food Therapy

Omega-3 fatty acids are very important in the treatment of laminitis. Hemp seed moistens the intestines to promote bowel movement, and is sweet and neutral. Flax and Chia seeds have similar effects. All of these have anti-inflammatory properties and help correct insulin and glucose usage.

Minerals

One of the most important aspects of any nutritional program for horses is the use of free choice minerals and salt fed separately. Many laminitis horses will eat large quantities of minerals for extended periods. Sulfur may be an important nutrient for these horses and can be fed free choice or in an MSM supplement.

Other Nutrients:

Antioxidants:  Vitamin C is an excellent antioxidant and supports the immune system healing. Coenzyme Q10 seems to one of the best antioxidants for use in horses, especially in cases of laminitis.

Chromium:

Chromium  has been found to be beneficial in diabetic experimental animals and also in conditions resulting from insulin sensitivity and defects in glucose transportation (Liu et al., 2010)

Source:https://dspace.library.colostate.edu/bitstream/handle/10217/65346/OtabachianSmith_colostate_0053N_11108.pdf?sequence=1&isAllowed=y

Electrolyte Loss & Replacement Strategies

Did you know a horse not in work loses up to 10 litres a day in sweat! That means losses of 10 grams of Sodium, 10 grams of Chloride, 25 grams of Potassium and 10 grams of Magnesium!

A horse in mid range work sweats by comparison 27-43 litres a day.  That means losses of up to 43 grams of Sodium, 71 grams of Chloride, 43 grams of Potassium and 13 grams of Magnesium.

Tying up is a common problems in performance horses. Research in England suggests tying up is related to electrolyte imbalances.

So how do you replace these significant electrolyte losses?  A portion of sodium and chloride can be obtained by providing a salt lick block.  Potassium can be picked up in forage, typically hay provides 10-20 grams per kg.  German research revealed horses fed adequate forage maintained better water and potassium balances during exercise than horses fed a high concentrate diet (Grain).

http://www.minrosa.com.au/pages/

Magnesium however is not readily available in sufficient quantities to replenish a horses needs.  Magnesium must be fed in conjunction with Calcium (close to 3:1 Calcium: Magnesium) in conjunction with Boron to be adequately supplied to and utilised by the small intestine.