Nutrition - supporting the recovery process to improve performance - Train, Race, Recover, Repeat

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Article by Dr Andy Richardson BVSc CertAVP(ESM) MRCVS

Introduction

Horses evolved as herd-living herbivores with a digestive tract designed to cope with a near continuous dietary input of forage in the form of a wide range of plant species. A large hindgut acts as a fermentation vessel where gut microbiota (predominantly a mix of bacteria, protozoa and fungi) exist in harmony with the horse in order to digest the fiber rich plant material.

Fiber is important to the horse for several reasons. The digestion of fiber releases energy and other key nutrients to the horse. Fiber also acts to provide bulk in the digestive tract, thus helping maintain the passage of fecal material through the system. Fiber also acts like a sponge to absorb water in the gut for release when required.

As horses became domesticated and used for work or sporting purposes, more energy-dense feeds in the form of cereal grains were introduced to their diet, as simple forage did not provide for all the caloric requirements. Cereal grains are rich in starch, which is an energy-dense form of nutrition. However, too much starch can cause problems to a digestive tract that remains designed for a pasture-based diet. The issues that can be caused by the trend away from a solely pasture-based diet can be digestive, behavioral or clinical.

Nonetheless, the combination of forage and cereal-based concentrates remains the mainstay approach for the majority of horses in training today, in order to maximize performance. A great deal of research and expertise are utilized by the major feed companies to ensure that modern racehorse concentrate feeds provide adequate provision of the major nutrients required and minimize unwanted effects of starch in the diet.

This article aims to discuss some scenarios where targeted or supplemented nutrition can act to help overcome some of the nutritional challenges faced by the modern horse in training, as they “Train, Race, Recover and Repeat.”

Equine Gastric Ulceration Syndrome (EGUS)

EGUS occurrence in racehorses is well documented, with prevalence shown to be over 80% in horses in training (Vatistas 1999). With a volume of approximately 2–4 gallons (7.53–15 liters), the stomach in horses is relatively small compared to their overall size due to its functional role in accommodating trickle feeding that occurs during their natural grazing behavior. 

As a horse chews, it produces saliva, which is a natural buffer for stomach acid. When the horse goes for a period of time without chewing, the production of saliva ceases, and stomach acid is not as effectively neutralized. The lower half of the stomach is better protected from acid due to its more resistant glandular surface. The upper, or squamous, region does not have such good protection, however, and this can be a problem during exercise when acid will physically splash upwards, potentially leading to gastric ulceration.

In practice, this can present a challenge for horses in training. Typically, they will be fed a concentrate-based feed in the early morning that stimulates a large influx of acid in order to help digest the starch. This may be followed by a period without ad-lib access to hay, thus reducing the amount of saliva subsequently produced to act as a buffer. When the horse is subsequently worked, there is a risk of acid damaging the upper squamous region of the stomach. There is some evidence to suggest that the provision of hay in advance of exercise may act like a sponge for the acid, as well as helping form a fibrous matt to minimize upward splash.

Gastric ulceration can go undetected in horses in training and may not lead to any obvious clinical signs. In other horses, it can lead to colic, poor appetite, dull coat and behavioral changes. In both scenarios, it is likely that the ulceration will have an impact on their performance, with decreased stride length, reduced stamina and inability to relax at speed all being possible consequences (Nieto 2009). Gastric ulceration can therefore have a significant impact on the ability of a horse to perform optimally day in day out in a training environment. This is exacerbated when ulceration leads to a reduction in appetite, with the obvious downside of a reduction in calorie intake leading to condition loss and further drop in performance.

This is an area where targeted nutrition has been clinically proven to play an important role. Ingredients such as pectin, lecithin, magnesium hydroxide, live yeast, calcium carbonate, zinc and liquorice have all been studied as having beneficial effects on gastric ulceration (Berger 2002, Loftin 2012, Sykes 2013). It is likely that a combination of the active ingredients will be most efficacious, with benefits noted when the supplement is added to the feed ration to help neutralize acid and form a gel-like protective coating on the stomach surface.

The daily administration of a targeted gastric supplement can be an important part of daily nutrition of the horse in training, alongside the use of pharmaceuticals such as omeprazole or esomeprazole when required.

Sweat loss

Horses have one of the highest rates of sweat loss of any animal, with sweat being comprised of both water and electrolyte ions such as sodium, potassium, chloride, magnesium and calcium. Therefore, it is not surprising that horses in training are at risk of unwanted issues should sweat loss not be replaced.

It is also worth noting that transportation can also lead to excessive sweat loss, with studies showing sweat rates of 5 liters per hour of travel on a warm day (van den berg 1998).

If the electrolytes lost in sweat are not adequately replaced, a drop in performance can result, as well as clinical issues such as thumps, dehydration and colic.

Electrolytes play key roles in the contraction of muscle fibers and transmission of nerve impulses. Horses without adequate electrolyte levels are at risk of early onset fatigue that may result in reduced stamina. It is also worth noting that horses that train on furosemide will have higher levels of key electrolyte losses, so will require targeted support to help maintain performance levels (Pagan 2014).

There is also evidence to suggest that pre-loading of electrolytes may be beneficial (Waller 2022). For horses in daily work, the addition of electrolytes to the evening feed will not only replace losses but also help optimize levels for the following day’s travel or race. The benefit of providing electrolytes with feed is that it will minimize the risk of the electrolyte salts irritating the stomach lining, which can occur if given immediately after exercise on an empty stomach. Feeding electrolytes when the horse is relaxed back in the stable will also allow them to drink freely, with the added benefit that electrolytes will stimulate the thirst reflex when they are relaxed, ensuring they are adequately hydrated for the following day.

Products should be chosen on the basis of adequate key electrolyte provision as not all products will provide meaningful levels of all the key electrolyte ions.

Muscle soreness

The process of muscle breakdown and repair is a normal adaptive response to training. This process can lead to inflammation and soreness or stiffness after exercise. In humans, there is a well-recognized condition called Delayed Onset Muscle Soreness (DOMS).

Further research is required to fully understand the impact of DOMS in horses. DOMS is the muscular pain that develops 24–72 hours after a period of intense exercise. There is no pain felt by the muscles at the time of exercise, in contrast to a ‘torn muscle’ or ‘tying-up’ for example.

In humans, DOMS is thought to be the result of tiny microscopic fractures in muscle cells. This happens when doing an activity that the muscles are not used to doing or have done it in a more strenuous way than they are used to.

The muscles quickly adapt to being able to handle new activities, thus avoiding further damage in the future; this is known as the “repeated-bout effect”. When this happens, the micro-fractures will not typically develop unless the activity has changed in some substantial way. As a general rule, as long as the change to the exercise is under what is normally done, DOMS are not experienced as a result of the activity.

In practice, avoiding any post-exercise muscle soreness in a training programme may be unavoidable, as exercise intensity and duration increases. Horses are far from being machines, so there is a fine balance between a programme that gets a horse fit for purpose without some post-exercise muscle discomfort. Physiotherapy, swimming and turnout will all likely benefit horses experiencing muscle discomfort. Whilst non-steroidal anti-inflammatories will always have their place for horses in training, one area of advancement is the use of plant-based phytochemicals to support the anti-inflammatory response (Pekacar 2021). These may have the benefit of not leading to unwanted gastrointestinal side effects and not having prolonged withdrawal times, although this should always be checked with any supplement particularly with the recent update regarding MSM.

Exercise will also lead to a process of muscle cell damage caused by oxidative stress. This is an inflammatory process and recovery from oxidative stress is key to allow for muscle cell repair and growth. Antioxidants are compounds that help recovery and repair of muscle cells following periods of intense exercise. The process of oxidative stress in muscle cells can lead to muscle fatigue and inflammation if left unsupported. Antioxidant supplementation in the form of Vitamin E or plant-based compounds can help protect against excessive oxidative stress and support muscle repair after exercise (Siciliano 1997).

Conclusion

Nutritional management of horses in training is a complex topic, not least as every horse is an individual and so often needs feeding accordingly. Whilst there is a lot of science available on the subject, the ‘art of feeding’ a racehorse—something that trainers and their staff often have in-depth knowledge of— remains an incredibly important aspect. Targeted nutritional supplements undoubtedly have their place, as discussed in, but not limited to, the scenarios above. 

Veterinarians, physiotherapists, other paraprofessionals and nutritionists all play a role in minimizing health issues and maximizing performance. In the quest for optimal performance on the track, nutritional support is one of the cornerstones of the ‘marginal gains’ theory that has long been adopted in elite human athletes. There is no doubt that racehorses themselves are supreme athletes that live by the mantra of Train, Race, Recover, and Repeat.


References

Berger, S. et al (2002). The effect of acid protection in therapy of peptic ulcer in trotting horses in active training. Pferdeheilkunde 27 (1), 26-30,

Loftin, P. et al (2012). Evaluating replacement of supplemental inorganic minerals with Zinpro Performance Minerals on prevention of gastric ulcers in horses. J.Vet. Int. Med. 26, 737-738

McCutcheon, L.J. and geor R.J. (1996). Sweat fluid and ion losses in horses during training and competition in cool vs. hot ambient conditions: implications for ion supplementation. Equine Veterinary Journal 28, Issue S22.

Nieto, J.E. et al (2009). Effect of gastric ulceration on physiologic responses to exercise in horses. Am. J. Vet. Res.70, 787-795.

Pagan, J.D. et al (2014). Furosemide administration affects mineral excretion in exercised Thoroughbreds. In: Proc. International Conference on Equine Exercise Physiology S46:4.

Pekacar, S. et al (2021). Anti-Inflammatory and Analgesic Effects of Rosehip in Inflammatory Musculoskeletal Disorders and Its Active Molecules. Curr Mol Pharmacol. 14(5), 731-745.

Rivero, J.-L.L. et al (2007). ‘Effects of intensity and duration of exercise on muscular responses to training of thoroughbred racehorses’. Journal of Applied Physiology 102(5), 1871–1882.

Siciliano, P.D. et al (1997). Effect of dietary vitamin E supplementation on the integrity of skeletal muscle in exercised horses. J Anim Sci.75(6), 1553-60.

Sykes, B. et al (2013). Efficacy of a combination of a unique, pectin-lecithin complex, live yeast, and magnesium hydroxide in the prevention of EGUS and faecal acidosis in thoroughbred racehorses: A randomised, blinded, placebo-controlled clinical trial. Equine Veterinary Journal, 45, 16.

van den Berg, J. et al (1998). Water and electrolyte intake and output in conditioned Thoroughbred horses transported by road. Equine Vet J. 30(4), 316-23.

Vatistas, N.J. et al (1999) Cross-sectional study of gastric ulcers of the squamous mucosa in thoroughbred racehorses. Equine Vet J Suppl. 29, 34–39.

Waller, A.P., and M.I. Lindinger. (2022). Tracing acid-base variables in exercising horses: Effects of pre-loading oral electrolytes. Animals (Basel) 13(1), 73.

Why are gastric ulcers still a significant concern for horses in training?

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With the advances in scoping and increased awareness of gastric ulcers, along with the high prevalence found in horses in training, one may wonder, Why is this condition still such a problem? Do we not know enough to prevent this condition from recurring? 

The short answer is that much is known, and for certain, there are effective medications and many feeds and supplements designed to manage the condition. The underlying problem is that the factors leading to ulceration, at least the most significant ones, are fundamental to the routine and management of a horse in training. Quite simply, the environment and exercise required are conducive to development of ulcers. Horses in training will always be at risk from this condition, and it is important to manage our expectation of how much influence we can have on ulcers developing, and our ability to prevent recurrence. 

Clarifying Gastric Ulceration

Before considering how and why ulcers are a recurrent problem, it is helpful to understand the different types of gastric ulceration as the term most commonly used, Equine Gastric Ulcer Syndrome (EGUS), is an umbrella term which represents two distinct conditions. 

The term EGUS came into use in 1999 and represented ulceration of the two separate locations in the stomach where ulcers are found: the squamous and glandular regions. The two regions are functionally different, and ulceration in either location has different causative factors. This is important when considering what can be managed from a risk point of view at a racing yard. The term EGUS is now split into two categories: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). 

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ESGD is the most commonly occurring form and the focus of dietary and management interventions. The majority of horses in training have the primary form of ESGD where the stomach functions normally. There is a secondary form that relates to a physical abnormality which causes delayed emptying of the stomach.

The condition ESGD is influenced by the training environment and time spent in training as noted by researchers looking at prevalence of horses out of training compared to those within training. In this case, 37% of untrained thoroughbred racehorses had ESGD and this progressed to 80-100% of horses within two to three months of training. This effect is not unique to thoroughbreds and is seen in other breeds with an ‘active workload’; for example, standardbreds progress from an average of 44% ESGD in the population to 87% when in training. Such research is helpful in understanding two things: firstly, that ulcers in the squamous section can occur outside of training, and that the influence of exercise and dietary changes have a significant effect regardless of breed. Even horses in the leisure category, which are thought of as low risk or at almost no risk at all, can return surprising results in terms of prevalence.

There are multiple risk factors associated with development of ESGD, some of which are better evidenced than others, and some of which are more influential. These include:

  • Pasture turnout

  • Having a diet high in fibre/provision of ‘free choice’ fibre

  • Choice of alfalfa over other forages

  • Provision of straw as the only forage source

  • Restricted access to water

  • Exceeding 2g of starch per kilogram of body weight 

  • Greater than 6 hours between meals (forage/feed)

  • Frequency and intensity of exercise 

  • Duration of time spent in a stabled environment combined with exercise

Of these factors, the stabled environment—which influences feeding behaviour—and exercise are the most significant factors. The influence of diet in the unexercised horse can be significant, however once removed from pasture, and a training program is entered into, ulceration will occur as these factors are more dominant. An Australian study of horses in training noted the effect of time spent in training, with an increase in risk factor of 1.7 fold for every week spent in training. 

Once in training, there is some debate as to whether provision of pasture, either alone or in company, has a significant effect. Some studies report a lower risk of ESGD when pasture in company is provided for horses in training, whereas others have found no significant effect. The duration of access and quality of pasture involved may be part of the differences in results found. There is a distinct difference between turnout in a paddock that offers a pick of grass and a leg stretch and a paddock rich in well managed pasture. Ultimately a period of turnout whilst in a training program is not enough of a counter-balance to the risks of frequent and intense exercise, coupled with a need for stabled periods and higher rates of compound feeding.

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Small but mighty - the role of antioxidants for horses in training

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Small but mighty The role of antioxidants for horses in trainingAntioxidants are substances that slow down damage to organisms created by the presence of oxygen. The need for antioxidants is always there, in all species, increasing as exercise intensity and duration increase. Is there merit in specifically supplementing antioxidants to enhance performance? The nature of antioxidantsThere are many forms of antioxidants naturally present within the body and supplied through the diet. One key feature of antioxidants is that they are ‘team players’. No one antioxidant alone can maintain the system, and some will only function in the presence of another antioxidant. The role of an antioxidant is to keep reactive oxygen species (ROS) or free-radicals created in the presence of oxygen at an optimum level. Oxygen is required for life, it is always present, but as an element, it is highly reactive and so can also have an adverse effect on the body. The reactivity of oxygen in the body produces ROS which cause damage to cellular components such as DNA, proteins and lipids of cell membranes. Some ROS also have useful cellular functions, and so the purpose of antioxidants is not to eliminate ROS altogether but to maintain a healthy balance. In general, antioxidants operate in two ways: either preventing the formation of an ROS or removing it before it can cause damage to a cell component.Sources of antioxidantsThere are multiple sources of antioxidants including vitamins, enzymes and nutrient derivatives. Other nutrients such as minerals, whilst not having antioxidant properties, are also involved as their presence is required for the functioning of antioxidant enzymes. Two key examples are zinc and selenium.Antioxidant ExamplesVitamin CVitamin ESuperoxide dismutase Glutathione peroxidaseLipoic acidGlutathioneUbiquinol (co-enyzme Q10)Oxidative stress Photo: horse exercising?As with many body systems, the ideal healthy balance can often go awry. When the level of ROS present overwhelms the capacity of antioxidants present, the body experiences oxidative stress. There are three main reasons for a horse in training experiencing oxidative stress:Increased exposure to oxidants from the environmentAn imbalance or shortage in supply of antioxidantsIncreased production of ROS within the body from increased oxygen metabolism during exerciseOxidative stress is of concern as it can exaggerate inflammatory response and may be detrimental to the normal healing of affected tissues. Oxidative stress during strenuous exercise, such as galloping or endurance, is typically associated with muscle membrane leakage and microtrauma to the muscle. Oxidative stress is now understood to play a role in previously unexplained poor performance.Dietary antioxidants photo: horse eating?Given the demands of training and the regularity of intense exercise and racing itself, the use of dietary antioxidants is an important consideration. As antioxidants are generally best considered as a cocktail, it is necessary to give consideration to provision of nutrients and their derivatives across the total daily diet. The majority of racing feeds will be formulated to provide a good cocktail of basic antioxidants or their supporting minerals. All feeds will contain vitamin E, selenium and zinc for example. Some, but not all, feeds will also provide vitamin C. The source of these nutrients may also differ; for example, some feeds will contain chelated zinc or organic selenium, which offer improved availability. The source of vitamin E will also vary—the majority being provided as synthetic vitamin E; but some will include natural sources of vitamin E, which is more effective. Once a good base diet is in place, consideration for strategic use of individual antioxidants may then be warranted to further enhance the capacity of the body to mitigate the effects of ROS on the muscle. Three popular and commonly used antioxidants are vitamin E, vitamin C and more recently coenzyme Q10.Vitamin EAs a lipid-soluble antioxidant, vitamin E provides defence against ROS in cells, playing an important role in maintaining integrity of cell membranes. Vitamin E is the most commonly supplemented antioxidant. There are established recommended daily intakes for vitamin E, typically 1000 IU per day for a horse in training; however, further supplementation beyond the basic nutritional requirement can yield benefits. Modern race horse feeds are well fortified—the majority providing upwards of 300 IU/kg, resulting in an average daily intake of over 2000 IU/day.Intakes of above the base rate have been investigated for their effect on CK (creatine kinase) and AST (aspartate aminotransferase)—two markers of muscle damage. One such study used endurance horses whereby intakes ranged from 1150 IU up to 4750 IU per day. Elevated intakes of vitamin E correlated with lower levels of CK and AST suggest that vitamin E can affect muscle membrane permeability and injury to muscle during exercise. As a guide to improving antioxidant capacity, an intake of up to 5000 IU per day would be appropriate for a horse in training. Vitamin E intake is influenced by the level of fats fed in the diet; and where additional oils are added, further vitamin intake E is required, as vitamin E will be utilised in stabilising the oil itself. Fats fed in a dry format, such as extruded rice bran, are normally fortified with vitamin E for this reason and do not require further supplementation. Vitamin E is available in feeds and supplements in two forms: synthetic or natural. The natural form, d-alpha-tocopherol, is made up of a single isomer (chemical unit). The synthetic form, dl-alpha-tocopherol, is made up of eight different isomers—only one of which is molecularly the equivalent of natural vitamin E. The dose rate required to increase serum vitamin E levels in horses is lower for natural E than synthetic vitamin E. Effect of feeding 5000 IU per day of a synthetic or natural vitamin E form (Nano-E) on serum vitamin EImage Source Kentucky Equine ResearchThe increased bioavailability of natural vitamin E has led to further research in comparing this source against synthetic vitamin E for efficacy against oxidative stress and physical gait changes. The study used 3 diets: a control diet with the standard recommended intake of 1000 IU/day provided by synthetic vitamin E; a higher intake synthetic vitamin E diet of 4000 IU/day; and a high intake of natural vitamin E at 4000 IU/day. The study lasted for six weeks and measured serum levels of vitamin E at various time points along with markers of oxidative stress, CK and AST levels, and gait analysis.The key findings:All diets increased serum vitamin E over time; however, the increase was not significant in the diet, providing only 1000 IU/day of synthetic vitamin E. The greatest difference in serum vitamin E was seen in the natural vitamin E diet where levels increased by 77.25% from day one to the last time point.Oxidative stress was measured through multiple tests including oxidation of lipids (TBARS). Horses supplemented with natural E had lower levels of lipid oxidation markers than both synthetically supplemented horses at the second exercise test, which occurred after six weeks of fitness training.AST levels were lower within the two hours post exercise of natural E supplemented horses compared to synthetic vitamin E horses; however, by 24 hours, the difference was no longer significant. There was no noted significant effect on CK. Gait analysis before and after exercise showed better movement of horses that were supplemented with natural vitamin E. These horses experienced less of a reduction in their stride duration post exercise, potentially indicating less muscle soreness due to less oxidative stress.As vitamin E is well proven to be an effective antioxidant, it may be tempting to think that ‘more is better’; however, as with all nutrients, there is a safety limit to consider. Current research indicates that supplementing at 10 times the base level—an intake of 10,000 IU/day—may result in poor bone mineralisation and impair beta-carotene (vitamin A) absorption. An intake of 4000-5000 IU/day based on the research above and other studies would appear effective whilst also being well below the presumed safety limit. Vitamin COrdinarily horses can manufacture adequate vitamin C within the body, unlike humans that require direct supplementation. Additional vitamin C is required and often recommended when the body is challenged through disease or periods of stress. Research has shown vitamin C is needed for horses with recurrent airway obstruction, horses following colic surgery and foals during weaning when stalled. The variety of situations in which vitamin C requirements increases is broad, and the demands and stressors of training make vitamin C an attractive supplement.Vitamin C is water soluble and has the advantage of being able to work both inside and outside the cell to combat free-radical damage. Whilst being an antioxidant in its own right, it also has another significant benefit relating to vitamin E. Vitamin C is somewhat ‘self-sacrificing’ and can regenerate spent Vitamin E, reviving it to an active antioxidant. The combination of vitamins E and C is therefore a common and well-established cocktail in certain feeds and antioxidant supplements. The benefits of combined supplementation have been documented in endurance horses racing 80km and also in polo ponies. What is important to note, is that when monitoring plasma levels of vitamin E and C within the polo ponies group, that supplementation was only successful in elevating serum levels in the hard working group when both E and C were supplemented. Those in hard work supplemented with vitamin E only did not see the same benefits. There is no set recommended daily intake for vitamin C as the body can synthesise enough for daily functions. The level of supplementation of vitamin C and the point at which it becomes effective will be in part dependent on other antioxidants present in the diet. Vitamin C is not easily absorbed, and to change blood ascorbate levels requires an intake of at least three grams per day. Research into racing endurance horses was effective at 7g per day fed in combination with 5000 IUof vitamin E. As a guide, based on research into various conditions benefiting from vitamin C, an intake of 5-10g per day would be suitable for a horse in training. Vitamin C supplementation may impact the body’s ability to naturally synthesise vitamin C, and so any period of supplementation of greater than 10 days should not be abruptly halted. If choosing to discontinue high intakes of vitamin C, the feed or supplement should be gradually transitioned downwards.Coenzyme Q10 (ubiquinone)Coenzyme Q10, also known as ubiquinone, is an effective antioxidant and has the ability to regenerate both vitamin E and vitamin C, making it an interesting addition to the diet. Unlike vitamin E and vitamin C, coenzyme Q10 is not a vitamin. It is synthesised in all body tissues, and the name ubiquinol given to this substance in 1975, is derived from the adjective ubiquitous—a nod to the compound’s widespread distribution in nature. Horses, when compared to humans, are naturally lower in coenzyme Q10 as measured in serum. Research in 2013 confirmed that supplementing with coenzyme Q10 could increase serum levels; in this particular study 800mg was given per day for 60 days. Further research looking at serum coenzyme Q10 following steady exercise or intense exercise (breezing) at dose rates of 1.9g per day, and 3.4g confirmed that supplementation raised serum profiles. Further to that confirmation, the serum levels post breezing were not as elevated, demonstrating that coenzyme Q10 was ‘spent’ during intense exercise periods. Coenzyme Q10 is the latest antioxidant to gain more attention and research specific to equines and is proving to be of interest in mitigating oxidative stress.More recently, a liquid form of coenzyme Q10 has been investigated by Kentucky Equine Research (KER) for its effects on a group of horses in training. Much like the conversation around vitamin E sources, the form of coenzyme Q10 also influences bioavailability with the liquid form being more available than the powdered form of crystallised ubiquinone. This study looked at energy production in skeletal muscle enzymes, showing an improvement when supplemented, and blood GGT levels. Gamma-glutamyl transferase (GGT) is an enzyme monitored in blood and is most commonly associated with liver damage; however, GGT is found in many body cells. Research is indicating a link with elevated GGT and poor performance of horses in training attributed to oxidative stress. GGT levels measured during the KER study of nano-Q10 showed that horses with higher serum coenzyme 10 had lower levels of GGT.Work in Ireland has also directly researched the effect in thoroughbreds, looking at a microactive form of Q10 and its effect on antioxidant enzyme presence in skeletal muscle. The most positive finding from this study was an increase in gene encoding of glutathione peroxidase isozymes. Glutathione peroxidase is a key enzyme in antioxidant defence systems. The study confirms that not only is coenzyme Q10 an antioxidant in its own right but that it can support defence systems through indirectly benefiting expression of other antioxidant enzymes. Coenzyme Q10 could perhaps be described as the ultimate team player when considering choosing an additional antioxidant to supplement. ConclusionThe use of a cocktail of dietary antioxidants is well warranted when considering an approach to reducing the effect of oxidative stress on muscles and in general recovery. It is important to understand what level and form of antioxidants are currently provided through your racing feed to establish the base daily intake and build from here upwards. The level of vitamin E, and possibly vitamin C, to consider supplementing will depend on the intake provided by the diet. Coenzyme Q10 is not found in racing feeds, is a straight addition to the diet and is certainly an excellent team player in terms of supporting regeneration of other key antioxidants. Reading ListCurley,C.E., Rooney,M.F., Griffin,M.E., Katz,L.M., Porter,R.K., Hill,E.W. (2018) Dietary supplementation with MicroActive Coenzyme Q10 increases expression of antioxidant genes in Thoroughbred skeletal muscle. Biochimica et Biophysica Acta (BBA) – Bioenergetics (1859) supplement, p45Fagan,M.M., Harris,P., Adams,A., Pzdro,R., Krotky,A., Call,J., Duberstein,K.J. (2020) Form of Vitamin E Supplementation Affects Oxidative and Inflammatory Response in Exercising Horses. Journal of Equine Veterinary Science (91)Geor,J. Harris,P. Coenen,M. (2013) Equine Applied and Clinincal Nutrition. China: ElsevierPagan, JD.(2006) Tocopherol form affects vitamin E. Feedstuffs 78 (2006)Sinatra,S.T., Stanley,N.J., Chopra,R.K., Bhagavan,H.N. (2014) Plasma Coenzyme Q10 and Tocopherols in Thoroughbred Race Horses: Effect of Coenzyme Q10 Supplementation and Exercise. Journal of Equine Veterinary Science (34) 2, p265-269

By Catherine Rudenko

Antioxidants are substances that slow down damage to organisms created by the presence of oxygen. The need for antioxidants is always there, in all species, increasing as exercise intensity and duration increase. Is there merit in specifically supplementing antioxidants to enhance performance?

• The nature of antioxidants

There are many forms of antioxidants naturally present within the body and supplied through the diet. One key feature of antioxidants is that they are “team players.” No one antioxidant alone can maintain the system, and some will only function in the presence of another antioxidant. The role of an antioxidant is to keep reactive oxygen species (ROS) or free-radicals created in the presence of oxygen at an optimum level. Oxygen is required for life; it is always present, but as an element, it is highly reactive and so can also have an adverse effect on the body. The reactivity of oxygen in the body produces ROS which cause damage to cellular components such as DNA, proteins and lipids of cell membranes. Some ROS also have useful cellular functions, and so the purpose of antioxidants is not to eliminate ROS altogether but to maintain a healthy balance. In general, antioxidants operate in two ways: either preventing the formation of an ROS or removing it before it can cause damage to a cell component.

• Sources of antioxidants

There are multiple sources of antioxidants including vitamins, enzymes and nutrient derivatives. Other nutrients such as minerals, whilst not having antioxidant properties, are also involved as their presence is required for the functioning of antioxidant enzymes. Two key examples are zinc and selenium.

Screenshot 2021-04-23 at 11.21.25.png

Oxidative stress

As with many body systems, the ideal healthy balance can often go awry. When the level of ROS present overwhelms the capacity of antioxidants present, the body experiences oxidative stress. There are three main reasons for a horse in training experiencing oxidative stress:

• Increased exposure to oxidants from the environment

• An imbalance or shortage in supply of antioxidants

• Increased production of ROS within the body from


100120_DERRINSTOWN STUD9 (1).jpg

increased oxygen metabolism during exercise Oxidative stress is of concern as it can exaggerate inflammatory response and may be detrimental to the normal healing of affected tissues. Oxidative stress during strenuous exercise, such as galloping or endurance, is typically associated with muscle membrane leakage and microtrauma to the muscle. Oxidative stress is now understood to play a role in previously unexplained poor performance. …

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“Bon Appétit” - how to encourage and maintain appetite throughout the season

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By Catherine Rudenko

Encouraging and maintaining appetite throughout aseason can become a serious challenge. The best planned feeding program in the world is of no use if the horse simply does not eat as required to sustain performance. There are multiple factors that can lead to poor appetite for horses in training – some relating to health, some relating to physical properties of the feed or forage, along with behavioral considerations.

What is a normal appetite?

Grain-based feeds are an important requirement for a horse in training.

Grain-based feeds are an important requirement for a horse in training.

Before we can fairly state a particular horse has a poor appetite, we must first have an idea of what a normal appetite range is. The horse has a given capacity within its digestive tract and an appetite appropriate to this. Horses will typically consume 2-3% of their body weight each day on a dry matter basis – in other words not accounting for fluid intake or any moisture found in the forages. This equates to 10-15kg (or 22-33lbs) per day for a 500kg-weight (or 1100lb) racehorse. As fitness increases, it is normal for appetite to reduce, and most horses will eat closer to 2% of their body weight. The energy requirement of a horse in training is such that they dependent on a large amount of grain-based “hard feeds,” which for the majority form 7-9kg (or 15-19lbs) of the diet each day. With a potential appetite of 10-15kg (or 22-33lbs) we are, for some individuals, running close to their likely appetite limit. The most immediate effect of a reduction in appetite is the reduction in energy intake. Horses require a large amount of calories, typically 26,000 to 34,000 cal per day when in full training. Comparatively, an average active human will require only 3,000 cal per day. Just one bowl of a racing feed can contain 4,500 cal, and so feed leavers that regularly leave a half or quarter of a bowl at each meal time really can be missing out. Forage is equally a source of calories, and a reduction of intake also affects total calorie intake.

• Physical form of feed and forage

The physical form of the bucket feed can affect feed intake due to simple time constraints. Morning and lunch time feeds are more common times at which to find feed left behind. Different feed materials have different rates of intake – due to the amount of chewing required – when fed at the same weight. To give an example, 1kg (or 2lbs) of oats will take 850 chews and only 10 minutes to consume in comparison with 1kg of forage taking up to 4,500 chews and 40 minutes to consume. Meals that require a high amount of chewing – while beneficial from the point of view of saliva production (the stomach’s natural acid buffer – can result in feed “refusal” as there is simply too much time required. Cubes are often eaten more easily as they are dense, providing less volume than a lighter, “fluffier” coarse mix ration. Inclusion of chaff in the meal also slows intake, which can be beneficial, but not for all horses. Any horse noted as a regular feed leaver ideally needs smaller meals with less chewing time. Keeping feed and forage separate can make a significant difference. The choice of forage is important for appetite. Haylage is more readily consumed, and horses will voluntarily eat a greater amount. The study below compares multiple forage sources for stabled horses. Another factor relating to forages is the level of NDF present. NDF (neutral detergent fiber) is a lab measure for forage cell wall content – looking at the level of lignin, cellulose and hemi-cellulose. As a grass matures, the level of NDF changes. The amount a horse will voluntarily consume is directly related to the amount of NDF present. Analyzing forage for NDF, along with ADF, the measure relating to digestibility of the plant, is an important practice that can help identify if the forage is likely to be well received. Alfalfa is normally lower in NDF and can form a large part of the daily forage provision for any horse with a limited appetite. As alfalfa is higher in protein – should it become a dominant form of daily fiber – then a lower protein racing feed is advisable. Racing feeds now range from 10% up to 15% protein, and so finding a suitable balance is easily done.

• B vitamins

B vitamins are normally present in good quantity in forages, and the horse itself is able to synthesize B vitamins in the hindgut. Between these sources a true deficiency rarely exists. Horses with poor appetite are often supplemented with B12 among other B vitamins. Vitamin B12 is a cofactor for two enzymes involved in synthesis of DNA and metabolism of carbohydrates and fats. Human studies where a B12 deficiency exists have shown an improvement in appetite when subjects were given a daily dose of B12.(3) As racehorses are typically limited in terms of forage intake and their hindgut environment is frequently challenged, through nutritional and physiological stresses, it is reasonable to consider that the racehorse, while not deficient, may be running on a lower profile. Anecdotal evidence in horses suggests B12 supplementation positively affects appetite as seen in humans. Another area of interest around B vitamin use is depression. Horses can suffer from depression and in much the same way as in the human form, this can affect appetite. …

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The importance of good nutrition for your staff

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By Lissa Oliver

Unique to the racing industry is the daily need for staff to meet required maximum weights. Many in racing already believe they understand nutrition and the best methods to make weight, using tried and tested practices that have been in common use for decades. The perceived success of such practices leads to an attitude of ‘it works for me’ and a reluctance to change or adopt new suggestions, and few consider the future consequences on health in later years.

Dehydrating and starvation to make weight is commonplace, and long periods in saunas and salt baths, laxatives and self-induced vomiting are familiar practices. The health implications associated with these include poor bone density, hormonal issues and impaired mood profile. Despite increased awareness of these problems, they remain as common globally as they were thirty years ago.

To help address this, the UK based Racing Foundation awarded a grant of just over £200,000 ($260,000) to support a ground-breaking, nutritional intervention programme developed over three years by a specialist team at the Research Institute of Sport and Exercise Sciences at Liverpool John Moores University. The team is led by former jockey, Dr George Wilson, and includes the head of nutrition for cycling’s Team Sky, Dr James Morton, and Daniel Martin, a doctoral researcher and high-performance nutritionist for the Professional Jockeys Association.

Dr Wilson has already spent seven years (part-funded by the Sheikh Mansoor Racing Festival) researching the serious health implications of extreme weight-making practises in jockeys and has designed healthier, alternative weight-making programmes. In addition to offering the facilities at the University to measure bone and body composition, hydration, metabolism and provide strength and fitness assessments, he also works with racing organisations to provide workshops, tests, presentations and bespoke advice. He is in the ideal situation to conduct research into the health issues faced by racing staff, having ridden as a steeplechase jockey in his younger days.

“For my first ride as a conditional (bug) jockey at Southwell in 1985, I lost a stone (14 lbs) in five days to make 10st (140 lbs) minimum weight, felt awful and, given the occupational risks, I shouldn’t have been near a horse, let alone riding in a race,” he reflects on his experience. He later rode as an amateur mostly in point-to-points and hunter chases when weight became a problem. “Having ridden over jumps, I fully empathise with staff and understand the need for, and risks from, dehydration and starvation. Riding out stable staff are weighed in some yards and most vacancies are advertised with a maximum weight, so making weight is not just a problem for jockeys but also for a lot of racing staff.

“I was aware that not a lot had changed since my own time in yards in the 1980s and 1990s and so I decided to do my doctorate in the effects of common weight-making practices such as dehydration and nutrition (or lack of!). In 2009 I started my first research and have now had 11 papers published.”

Currently, Dr Wilson is studying the effects of diet, dehydration and bone health of jockeys, but, as he recognises, comparisons of bone density between standard 12st (168 lb) athletes and 9st, (126 lb), jockeys may have potential flaws given jockeys are an atypical population, being much smaller athletes. Furthermore, unlike other athletes, jockeys don’t tend to perform substantial hard surface training that helps maintain healthy bone metabolism.

Assisting Dr Wilson is Daniel Martin, and their paper, Qualitative Research in Sport, Exercise and Health (31 August 2017), is the first body of research to investigate the opinions and practices of racehorse trainers in relation to rider welfare. Disappointingly for the researchers, from over 400 invitations, only five trainers expressed an interest to take part, something that certainly needs addressing.

A reluctance to face up to industry problems isn’t new and is not confined to trainers. “When I first went to the British racing industry authorities and said I wanted to do this, they originally didn’t offer any help,” he reveals. “There appeared to be a reluctance to accept that the current services and advice to help riders, particularly with weight-management, were clearly not working. Therefore, I just ‘kicked on’ with my research, and because jockeys had not received the sports science support in the past, they flocked to LJMU to undergo the testing and receive bespoke weight-management programmes.

“Thankfully, now everyone is aware of the issues and have embraced the research findings on healthier weight-management practices, and it appears we are all singing from the same hymn sheet. Indeed, Dr Jerry Hill, the Chief Medical Advisor at the British Horseracing Authority, is a collaborator on some of my recent published research and we have some other research projects we are currently working on together.”

Even so, it is an industry culturally-driven and based on the shared knowledge and experience of its senior professionals, which can represent an obstacle to Dr Wilson and his team when some of that knowledge is outdated and incorrect. As Martin explains within one of the published papers, “If apprentice and conditional jockeys can carry some knowledge of evidence-based practices and the dangers of traditional methods into their early careers, there will be less of a reliance on seeking advice from senior jockeys. Similarly, over time the ‘new’ practices will hopefully supersede the current archaic medley of dehydrative methods.”

It certainly behoves trainers to ensure that younger staff members are set good examples and it isn’t asking too much of their time or level of expertise to provide suitable meals, in yards where catering is offered. Where meals are not provided, posters and literature should be made available to display in the yard to help encourage awareness of a good diet.

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From fertility to foal - Considerations for digestive tract health

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By Emma Hardy, PhD

The success or failure of any breeding program is dependent on the nutritional status and digestive tract health of foals, mares, and stallions alike. Although this aspect of the operation is often overlooked, it is only by ensuring that these considerations are optimised that foals are given the best chance to survive and thrive, from birth through weaning and on to sale.   

A weighty issue

There exists surprisingly little research surrounding the nutrient requirements of the breeding stallion. This may be in part complicated by the great variation in activity; some stallions may serve several mares a day during peak periods in the breeding season, while others may serve only that number in a year. Other influencing factors may include temperament, management routine, and competitive activities. However, it is generally agreed that energy demands are indeed above maintenance levels, and according to various National Research Council studies it has been suggested that active stallions require approximately a third more digestible energy than their non-breeding, sedentary counterparts.  

Research in other species has shown that a body condition that deviates greatly from the ideal can be associated with an increased risk of infertility (Nguyen et al. 2009). Nutritional content is also of great importance, with zinc and omega-3 fatty acids playing important roles in sperm motility, mobility, and viability.

Extremes in body weight and condition can also affect the fertility of broodmares. Low levels of body fat in mares can inhibit or delay ovarian activity, and obesity is often associated with insulin resistance (equine metabolic syndrome, or EMS), which can also disrupt cyclicity. Gentry et al. (2002) found that mares with a body score of 3-3.5 demonstrated a longer anaestrus than mares with a good body score (eg., 5) (Henneke et al. 1983) and was accompanied by lower plasma leptin, prolactin, and insulin-like growth factors.

It would therefore be sensible to carefully manage the weight and condition of both broodmares and stallions to optimise breeding potential.

Safely improving body condition and weight

For horses struggling to maintain ideal body condition it is important to assess forage intake and quality, and to also increase concentrates. Energy-dense grains and fats are often employed in these situations; however, caution must be taken to avoid the digestive tract issues these can cause.

Adding fat-fortified feeds to the diet, or top dressing fats or oils, can be an effective way to increase caloric intake. However, oils can pose a palatability issue. For a significant caloric contribution, somewhere between 200-500 ml/day of vegetable oil would be required. This would also increase the need for additional vitamin E and selenium to counteract the greater antioxidant need of a horse on such levels of supplementation.

The horse is naturally limited in its capacity to digest large volumes of starch, so concentrations should be limited to about 2g starch/kg body weight per meal, which equates to 0.2% starch or 1.4kgs of grain per meal. Anything over this risks starch bypass through to the large intestine, which can cause a bacterial inversion and ultimately a range of issues from poor feed absorption and inflammation to colic and laminitis.     

While it is prudent to ensure that a diet is appropriate both in volume and quality, the health of the digestive tract itself can sometimes be overlooked.  Optimal absorption can only be maximised when the mucosal surface of the tract and its vascular supply is healthy, the structure facilitates effective nutrient uptake, and the transit rate allows adequate time for digestion.

Other factors known to affect fertility and gestation can include naturally occurring contaminants found in feed, bedding, and housing. It has been well established that exposure to toxins produced by moulds and yeast can have detrimental effects on many biological systems. Of particular interest to breeders are mycotoxins, such as ergotalcaloids (found in some species of grass) and zearalenone (occurring in cereals). Zearalenone disrupts the oestrous cycle leading to lower conception rates, and ergotalcaloids can induce late gestation fetal loss and placental abnormalities. Mycotoxin binding agents can be a beneficial addition to a broodmare’s diet in a bid to combat mycotoxicosis. Biological products such as yeast cell wall, containing polysaccharides such as glucan or mannan, are emerging as potent adsorbers, with multibinding properties to numerous chemically different mycotoxins (Diaz & Smith, 2005).

Clearly, risk management should be applied at all levels of the feed production and manufacture chain to minimise contamination. Correct storage and regular quality assessment are paramount but the addition of a mycotoxin absorbent to the diet is also likely to be beneficial.

Nutritional demands of the pregnant mare

The nutrient and energy requirements of the pregnant mare begin to increase from month five of gestation (as placental tissues significantly develop). Consequently, a carefully devised diet containing adequate protein, vitamins, and minerals (major and trace) is imperative.

The pregnant mare’s caloric intake should also be increased and, depending on climate, housing, etc., feed volume may need to be increased by up to 30% by the end of gestation. This may be complicated during late gestation when the foal occupies an increasing proportion of the mare’s abdominal cavity, thus making large volumes of feed difficult to ingest.

The foal will gain approximately 80% of its birth weight during the last trimester, and the most rapid growth period will be in the few days before or after birth (Staniar et al. 2004). Ensuring optimal gastrointestinal support helps to safeguard the health of both the mare and her foal.  

Colostrum IgG transfer crucial to foal health…

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Developing the two-year-old's foot

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The Carb Conundrum - feeding a low or high starch diet

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Bran mashes - Useful tradition or nutritional pariah?

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The attraction of this equine equivalent of a warm bowl of oatmeal or cup of hot chocolate has endured despite the many other changes in feeding practices over the years.

In its most common form a bran mash consists of a warm sloppy mixture of wheat bran, with other minor ingredients such as rolled barley, linseed, vegetable oil, honey, molasses or date syrup often being added. The exact recipe for a particular yard's bran mash is often a closely guarded secret, being regarded as part of a winning formula, and it could have been handed down through the generations of trainers.

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THIS ARTICLE FIRST APPEARED IN - NORTH AMERICAN TRAINER - ISSUE 27

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Author: Cath Dunnett


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To beet or not to beet? Will beetroot become part of the racehorse’s diet?

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Can nutrition give horses that first-class travel experience?

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TRAVEL, whether by road,air, train, or sea, is a routineexperience for most horses intraining. For some, travelmay be limited to relativelyshort journeys by road to race meetingswithin their home country, while otherhorses globetrot around the world…

While transporting horses by road to the local racecourse or by air to another part of the world is now a routine affair, the end result can still be stressful enough to have a detrimental effect on a horse’s health and performance on the racetrack. Catherine Dunnett Bsc, Phd looks at ways nutrition can help the horse have a more comfortable experience.

By Catherine Dunnett Bsc, Phd

First Published (20 October 2010 - Issue Number: 18)

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