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

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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Can nutrition influence EIPH? - alternative and supportive therapies as trainers seek to find other means of reducing the risk or severity of EIPH

EIPH (exercise-induced pulmonary haemorrhage) was first identified in racehorses in the 16th century. Since this time, the focus has been on mitigating the haemorrhage. Management of EIPH largely revolves around the use of furosemide, dependent of jurisdiction, may or may not be used on the day of racing. Alternative and supportive therapies are becoming increasingly popular as trainers seek to find other means of reducing the risk or severity of EIPH.Nutrition and plant-based approaches are part of an alternative management program. Whilst research is somewhat limited, the studies available are promising, and no doubt more work will be done as using furosemide becomes more restricted. There are several directions in which nutrition can influence risk for EIPH, including inflammatory response, blood coagulation, cell membrane structure, hypotension and reducing known lung irritants.The various approaches are all supportive, working on altering an element of risk associated with the condition. Some are more direct than others, focusing on the effect on red blood cells, whilst others work on some of the broader lung health issues such as reducing mucus or environmental irritants.None are competitive with each other, and there may be an advantage to a ‘cocktail’ approach where more than one mode of action is employed. This is a common practice with herbal-based supplements where the interactive effects between herbs are known to improve efficacy.Cell membraneThe red blood cell membrane—the semipermeable layer surrounding the cell—is made up of lipids and proteins. The makeup of this membrane, particularly the lipid fraction, appears to be modifiable in response to dietary fatty acids. Researchers feeding 50mls of fish oil found a significant increase in the percentage of omega-3’s in the cell membrane.Essential fatty acids (EFA’s), omega 3 and omega 6, are important cell membrane components and determine cellular membrane fluidity. Fluidity of a cell membrane is important, particularly when pressure increases, as a cell membrane lacking in fluidity is more likely to break. A cell that can deform, effectively changing rather than breaking, has an advantage and is linked with improved exercise performance in human studies. Inclusion of fish oil in the diet increases the ability of red blood cells to deform.Kansas State University investigated the effect of omega supplementation on 10 thoroughbreds over a five-month period. The diet was supplemented with either EPA and DHA combined, or DHA on its own. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are specific forms of omega-3 fatty acids commonly found in oily fish. When supplementing the diet with both EPA and DHA, a reduction in EIPH was seen at 83 days and again at 145 days. Feeding DHA on its own did not produce an effect.Fish oil contains both EPA and DHA and is readily available, although the smell can be off-putting to both horse and human. There are flavoured fish oils specifically designed for use in horses that overcome the aroma challenge and have good palatability.Inflammatory response and oxidative stressAirway inflammation and the management of this inflammatory process is believed to be another pathway in which EIPH can be reduced. Omega-3 fatty acids are well evidenced for their effect in regulation of inflammation, and this mode of action along with effect on cell membrane fluidity is likely part of the positive result found by Kansas State University.Kentucky Equine Research has investigated the effect of a specific fish oil on inflammatory response with horses in training. The study supplemented test horses with 60mls per day and found a significant effect on level of inflammation and GGT (serum gamma-glutamyl transferase). GGT is an enzyme that breaks down glutathione, an important antioxidant. As GGT rises, less glutathione is available to neutralise damaging free radicals, creating an environment for oxidative stress.A horse’s red blood cells are more susceptible to oxidative stress than humans, and maintaining a healthy antioxidant status is important for function and maintenance of cell integrity.Supplements for bleeders will often contain relatively high doses of antioxidants such as vitamin C and vitamin E to support antioxidant status in the horse and reduce risk of damage to cell membranes. Vitamin C has also been shown to benefit horses with recurrent airway obstruction and increase antibody response. Dose rates required for an effect range from 15-20g per day. If including high doses of vitamin C in the diet, it is important to note that any sudden withdrawal can have negative effects. Gradual withdrawal is needed to allow the body’s own mechanisms for vitamin C production to recognise and respond to the change in status.Rosehips are natural potent antioxidants containing many active substances. Research into the effect of rosehips specifically on red blood cells has shown they have a high efficacy when assessing their ability to ameliorate cell damage.Note – dreamstime image of rosehip berries as an exampleHypotensive herbsThe essential oil of caucus carota species is a well-documented oil having a hypotensive, lowering of blood pressure effect along with antifungal properties. Its antifungal effects are noted against aspergillus species, a common cause of poor respiratory health. Allium sativum is also well known for its ability to lower blood pressure. An initial study (data unpublished) into the effects of these two plants along with herbs reported to alleviate mucus in the lungs has shown promising results in a group of horses in training.Image idea – wild carrot plantProlonged blood coagulationAs prolonged blood coagulation is cited as a possible factor for EIPH, herbal products that are noted for their ability to enhance coagulation are in certain parts of the world widely used as part of managing EIPH.It is believed that increased clotting time during exercise-induced injury may exacerbate the severity of EIPH as a result of the delayed sealing of damaged micro vessels. This effect, where exercise diminishes the ability of equine platelets to respond to platelet aggregating factors, occurs in both horses known with EIPH and those with no history or apparent presence of EIPH.Pop out text boxPlatelet = synonymous with thrombocytes, a component of blood whose function is to stop bleeding by clumping and clotting blood vessel injuries.Aggregating factor = substances such as adenosine diphosphate, collage and platelet activating factor involved in triggering and mediating the clotting process.Researchers at Kansas State University have investigated two herbs for efficacy on severity of EIPH with a small number of thoroughbreds. The two herbs considered were notoginseng and bletillae. Both herbs are documented to reduce thrombin time, which relates to the time taken to form clots, and to reduce bleeding time. The study of five horses showed no effect in terms of severity of bleeding or preventing bleeding based on bronchoalveolar lavage (BAL) results. This may indicate that impaired haemostasis—the ability to stop blood flow—was not the primary cause of EIPH or that the herbs were not effective in addressing coagulation as a problem.Studies of both known bleeders and those without a history of bleeding have shown that all horses when strenuously exercised will experience some degree of bleeding. With this in mind, the coagulation theory is debated as to whether it is a primary factor in EIPH. It is difficult to prove conclusively that impaired coagulability exists in exercising horses for a number of reasons, including timing of sampling and how the body adapts through increased fitness and exercise intensity. Without specific and more conclusive evidence available, use of such herbs becomes a field study—a case of trying and seeing first hand whether an impact is made.Pop out text boxThrombin = an enzyme found in blood plasma which causes the clotting of blood.AmmoniaAmmonia is a known respiratory irritant linked with poor respiratory health. Exposure to ammonia results in increased mucin production and reduced pulmonary clearance. Excess protein intake in the diet increases nitrogen presence in urine and faeces, which can be volatilised to ammonia.To understand protein intake, it is necessary to analyse forage and calculate contribution alongside any hard feed or straights. Excessive protein can also impact performance by causing changes in blood pH. A shortage of protein is equally detrimental, and dropping down to a lower protein feed should only be considered once the total contribution is understood. The majority of horses in training will receive above the base requirement for protein, and in moderation over-provision can have its advantages, such as improved recovery and refuelling of muscle. It is important to understand the difference between an elevated intake and an excessive intake.Image – racehorse barn / stabled racehorsePop out text boxPulmonary clearance = the ability of cells within the lungs to propel mucus and debris upwards and out of the lungs.SummaryThere is a role for nutrition and plant-based therapies in management of EIPH with strong evidence as their effects on cell membranes, regulation of inflammation, ability to reduce bleeding time and hypotensive effects. The balance of dietary protein is also a factor when considering how to manage general respiratory health, which in turn plays a role in managing the risk of EIPH.Getting the best result for horses suffering with EIPH will involve a cocktail approach reviewing the diet and supplements as a whole. Assessing total protein intake and including fish oil, containing both EPA and DHA, are two easy practices to put in place. Targeted use of antioxidants, hypotensive herbs, coagulative herbs and those involved in mucus clearance can then be built around the base diet changes.The aim of such practices is to reduce the severity and frequency of bleeding so that the limitations that EIPH has on performance are reduced. Nutritional and plant-based approaches require a period of adaptation, with some studies noting effects only after a month of use, and so patience and planning are required. For known bleeders, ideally all dietary practices and supplements should be put in place as soon as the horse returns from a holiday period, rather than waiting for full work to commence or for a serious incidence of EIPH to occur.Reading ListAlves-Silva,J.M., Zuzarte,M. Gonclaves,M.J. Cavaleiro,M.T.C., Cardoso,S.M., Salguerio,L. (2016). New claims for wild carrot (daucus carota subsp. carota) essential oil. Evidence-Based Complementary and Alternative Medicine.Epp,T.S, McDonagh,P. Padilla,D.J., Cox,J.H., Poole,D.C., Erickson,H.H. (2004). The effect of herbal supplementation on the severity of exercise-induced pulmonary haemorrage. Equine and Comparative Exercise Physiology 2(1): 17-25Erickson,H.H., Epp,S.T. Poole,D.C.(2007) Review of Alternative Therapies for EIPH. AAEP Proceedings (7)Geor,J. Harris,P. Coenen,M. (2013) Equine Applied and Clinical Nutrition. China: ElsevierPortier,K., De Moffarts,B., Fellman,N., Kirschvnik,N., Motta,C., Letellier,C., Ruelland,A., Van Erck,E., Lekeux,P., Coudert,J. (2006). Equine Veterinary Journal Supplement, Equine Exercise Physiology 7.Widen,C. Ekholm,A., Coleman,M.D., Renvert,S., Rumpunen,K. (2012). Erythrocyte Antioxidant Protection of Rose Hips (Rosa spp.). Oxidative Medicine and Cellular Longevity.

By Catherine Rudenko

EIPH (exercise-induced pulmonary haemorrhage) was first identified in racehorses in the 16th century. Since this time, the focus has been on mitigating the haemorrhage. Management of EIPH largely revolves around the use of furosemide, dependent of jurisdiction, may or may not be used on the day of racing. Alternative and supportive therapies are becoming increasingly popular as trainers seek to find other means of reducing the risk or severity of EIPH.

Nutrition and plant-based approaches are part of an alternative management program. Whilst research is somewhat limited, the studies available are promising, and no doubt more work will be done as using furosemide becomes more restricted. There are several directions in which nutrition can influence risk for EIPH, including inflammatory response, blood coagulation, cell membrane structure, hypotension and reducing known lung irritants.

Screenshot 2020-10-24 at 11.44.12.png

The various approaches are all supportive, working on altering an element of risk associated with the condition. Some are more direct than others, focusing on the effect on red blood cells, whilst others work on some of the broader lung health issues such as reducing mucus or environmental irritants. 

None are competitive with each other, and there may be an advantage to a ‘cocktail’ approach where more than one mode of action is employed. This is a common practice with herbal-based supplements where the interactive effects between herbs are known to improve efficacy. 

Cell membrane

The red blood cell membrane—the semipermeable layer surrounding the cell—is made up of lipids and proteins. The makeup of this membrane, particularly the lipid fraction, appears to be modifiable in response to dietary fatty acids. Researchers feeding 50mls of fish oil found a significant increase in the percentage of omega-3’s in the cell membrane.

Essential fatty acids (EFA’s), omega 3 and omega 6, are important cell membrane components and determine cellular membrane fluidity. Fluidity of a cell membrane is important, particularly when pressure increases, as a cell membrane lacking in fluidity is more likely to break. A cell that can deform, effectively changing rather than breaking, has an advantage and is linked with improved exercise performance in human studies. Inclusion of fish oil in the diet increases the ability of red blood cells to deform.

Kansas State University investigated the effect of omega supplementation on 10 thoroughbreds over a five-month period. The diet was supplemented with either EPA and DHA combined, or DHA on its own. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are specific forms of omega-3 fatty acids commonly found in oily fish. When supplementing the diet with both EPA and DHA, a reduction in EIPH was seen at 83 days and again at 145 days. Feeding DHA on its own did not produce an effect.

Fish oil contains both EPA and DHA and is readily available, although the smell can be off-putting to both horse and human. There are flavoured fish oils specifically designed for use in horses that overcome the aroma challenge and have good palatability. 

Inflammatory response and oxidative stress

Kentucky Equine research results

Kentucky Equine research results

Airway inflammation and the management of this inflammatory process is believed to be another pathway in which EIPH can be reduced. Omega-3 fatty acids are well evidenced for their effect in regulation of inflammation, and this mode of action along with effect on cell membrane fluidity is likely part of the positive result found by Kansas State University. 

Kentucky Equine Research has investigated the effect of a specific fish oil on inflammatory response with horses in training. The study supplemented test horses with 60mls per day and found a significant effect on level of inflammation and GGT (serum gamma-glutamyl transferase). GGT is an enzyme that breaks down glutathione, an important antioxidant. As GGT rises, less glutathione is available to neutralise damaging free radicals, creating an environment for oxidative stress.

A horse’s red blood cells are more susceptible to oxidative stress than humans, and maintaining a healthy antioxidant status is important for function and maintenance of cell integrity.

Rosehip

Rosehip

Supplements for bleeders will often contain relatively high doses of antioxidants such as vitamin C and vitamin E to support antioxidant status in the horse and reduce risk of damage to cell membranes. Vitamin C has also been shown to benefit horses with recurrent airway obstruction and increase antibody response. Dose rates required for an effect range from 15-20g per day. If including high doses of vitamin C in the diet, it is important to note that any sudden withdrawal can have negative effects. Gradual withdrawal is needed to allow the body’s own mechanisms for vitamin C production to recognise and respond to the change in status.

Rosehips are natural potent antioxidants containing many active substances. Research into the effect of rosehips specifically on red blood cells has shown they have a high efficacy when assessing their ability to ameliorate cell damage.

Hypotensive herbs

Caucus carota – wild carrott

Caucus carota – wild carrott

The essential oil of caucus carota species is a well-documented oil having a hypotensive, lowering of blood pressure effect along with antifungal properties. Its antifungal effects are noted against aspergillus species, a common cause of poor respiratory health. Allium sativum is also well known for its ability to lower blood pressure. An initial study (data unpublished) into the effects of these two plants along with herbs reported to alleviate mucus in the lungs has shown promising results in a group of horses in training. 

Prolonged blood coagulation

As prolonged blood coagulation is cited as a possible factor for EIPH, herbal products that are noted for their ability to enhance coagulation are in certain parts of the world widely used as part of managing EIPH. …

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Nutrition - how to rein in your complex carb intake for times when work drops

Starch or FibreBalancing different carbohydrate sources against changing requirements of fitness, injury and recoveryCarbohydrates are by far the largest component of any horse’s diet, typically two thirds by weight, yet we often focus more on other nutrients, such as protein—which in comparison forms only a small portion of the total diet at around 8-13%. Carbohydrates, specifically the balance between differing carbohydrate sources, influences three key areas relating to performance.The choice of carbohydrate influences the type of energy available, providing varying proportions of ‘fast release’ or ‘slow release’ energy. The type of carbohydrate chosen also impacts behaviour, increasing or decreasing risk of excitability and certain stereotypical behaviours. Last, but by no means least, the choice of carbohydrate and the way in which it is fed impacts digestive health and the ability of the digestive system to convert food to ‘fuel’ for the body.Getting the balance right between the different types of carbohydrates is important for getting the right results when having to adjust the intensity of training, when resting a horse and when working back up through the stages of fitness.What are carbohydrates?There are different ways of classifying or grouping carbohydrates, depending on whether you take things from the plant’s point of view or that of the digestive anatomy of the horse. Working with the horse in mind, carbohydrates are best classified by the section of the digestive system that they are processed in—either the small intestine or large intestine. The site of digestion determines the type of energy provided, often referred to as fast releasing for the small intestine and ‘slow releasing’ for the large intestine. The group of carbohydrates, known as hydrolysable carbohydrates, are the group behind the description of fast releasing, whilst the group known as fermentable carbohydrates are those forming the ‘slow releasing’ category. Within the fermentable group, there are three sub groups of rapid, medium and slow. What are carbohydrates made of?There are many types of carbohydrates in the horse’s diet, ranging from simple sugars to more complex structures. They are defined by their degree of polymerisation, which refers to the way in which sugar units are joined together. How a carbohydrate is formed and the type of link present are important as they determine if digestion is possible in the small intestine or whether fermentation in the large intestine is required. This influences the type of energy available.For horses in training, the type of carbohydrate of particular interest is the polysaccharide group which includes starch, cellulose, hemicellulose and fructans amongst others. Starch is found in significant quantities in hard feeds, whilst cellulose and hemicellulose, amongst other fermentable carbohydrates are abundant in forages. Pasture is a source of fructans, which can change rapidly depending on growing conditions and daylight hours.StructureSingle sugars, also called simple sugars, comprise one unit only. They are categorised as monosaccharides—the most commonly known being glucose. For horses in training this is a highly valuable sugar as it is the main ‘fuel’ for muscles. Glucose forms the basis of many of the more complex structures of interest to horses in training.When two sugars join together, they are known as a disaccharide—the best known being lactose which is found in mare’s milk. Oligosaccharides refer to more complex structures where more units are joined together—a common example being fructo-oligosaccharide (FOS) which many horses in training are specifically fed as a prebiotic to support digestive function.Type of CarbohydrateExampleMonosaccharideGlucose, FructoseDisaccharideLactose, Sucrose, MaltoseOligosaccharideFructo-Oligosaccharide (FOS)PolysaccharideStarch, Cellulose, FructansPolysaccharides, our group of particular interest, are significantly more complex chains that are branched and are not so easily digested as the simple sugars. The branched nature of polysaccharides, such as starch and cellulose, are the result of links between chains of sugars. The type of link present determines whether or not it will be possible for the horse to digest this form of carbohydrate in the small intestine or not.Giles – ideally image of flat racing next to starch sectionStarchStarch is the primary carbohydrate of interest in our hard feeds. It is a hydrolysable carbohydrate, which can be digested in the small intestine, releasing glucose into the bloodstream. For horses in training this is the most important fast release energy source. Starch is found in all plants, with the highest quantities seen in cereals such as oats, barley and maize.Composition of cereals commonly used in racing feedsOatsBarleyMaizeWheatProtein%911811Fibre%11.34.822Oil%6.82.642.3Starch%3851.56360Starch is made up of two types of sugar chains: amylose and amylopectin, which are formed from glucose units. Amylose itself is easily digested, however amylopectin has a different type of bond connecting each branch, which the enzymes of the small intestine cannot break down. Feed processing, which changes the structure of starch and breaks apart the previously indigestible bonds, is therefore a key factor in ensuring that when starch is fed that the maximum amount of glucose is derived.Amylose and Amylopectin Feed processing comes in many forms, from simply crushing or rolling the grain to cooking techniques including micronizing, steam flaking, pelleting or extruding. The amount of processing required for what is deemed efficient digestion differs by grain type. Oats have a natural advantage within the cereal group as they can be fed whole, although processing can still improve digestion. Barley, wheat and maize cannot be fed whole or simply rolled. They require cooking to ensure that starch becomes available, and the impact of cooking processes is much greater for these grains.The availability of starch is assessed through the amount of glucose released into the blood after feeding. The study below shows the effect of steam cooking maize (corn) compared to two processes that simply change the physical appearance, cracking or grinding. Steam-flaked maize is more available as shown by the greater glucose response.Starch is a fast release energy source, being digested in the small intestine, and the term can easily be misunderstood. It does not mean that the horse will suddenly run at top speed nor appear to be fuelled by ‘rocket fuel’. The word ‘fast’ relates to the relatively short time it takes for digestion to occur and glucose to be available. Looking at the maize example, it is possible to see that glucose is found in the blood just 30 minutes after feeding. This is a rapid response compared to carbohydrates that are digested further down the digestive tract in the large intestine.Energy is energy, whichever source it comes from or how long it takes to digest. However, the type of energy, whether fast release or slow release, does impact behaviour, in particular affecting reactivity. When fed on higher-starch diets, horses are well documented to become more reactive, anxious and over excitable. Aside from the need for glucose as a fuel for performance and equally for recovery, its presence in the diet can increase reactivity. In a sport where speed and the ability to react quickly are an advantage, starch and its associated effects can be a positive. Like all nutrients, there is a fine balance to be had, and an excess of starch and over excitable behaviour are not desirable at certain stages of fitness. Starch excess should be avoided at all costs for horses prone to tying-up where excitable behaviour is a known risk factor.Giles – ideally image of national hunt racing next to fermentable carbohydrate sectionFermentable carbohydratesCellulose, as an example of the fermentable carbohydrate group, is similar to starch being composed of glucose units, however the type of bond is significantly different and can only be digested in the large intestine through bacterial fermentation. Cellulose is a key component of the cell wall of plants, including both cereals and forages but is found in the highest amounts within forages and some of the more fibrous co-products used in feeds, such as sugar beet pulp.The digestive process of bacterial fermentation that occurs in the large intestine yields different energy sources in comparison to the small intestine where glucose is the main product of starch digestion. Fermentation of cellulose and other fermentable carbohydrates, such as hemicellulose and lignocellulose, produce volatile fatty acids (VFAs). Like glucose, these are an energy source for the horse but through different pathways. The time required for digestion in the large intestine is much greater than the small intestine, hence the term ‘slow release’ energy being applied to the fermentable carbohydrate group. Fibrous foods are typically processed over a 30-hour period in the hindgut.As the process of digestion and energy release is more gradual and does not result in a spike of glucose, the use of more fibrous carbohydrate sources is ideal when looking to provide energy in a more consistent format. Resting and early stages of work are best supported by a higher inclusion of fermentable carbohydrates. Equally once fit to avoid a situation in which the horse ‘boils over’, altering the main diet to marginally reduce starch and increase more fibrous fermentable carbohydrates can be of help.Cellulose and other fermentable carbohydrates are not analysed separately in the same manner as starch. Cellulose and lignocellulose are identified through a lab method known as acid detergent fibre (ADF). By looking at ADF and starch values, we can get a picture of the balance between the fast release and slow release sources that materials commonly fed to horses have. Cereals naturally provide more starch, whereas beet and alfalfa provide little starch but plenty of fermentable carbohydrates.Feeding IngredientStarch (%)ADF (%)Alfalfa231Sugar Beet1.525Wheatfeed2212Oats3816Barley505.5Through altering the amount of hard feed against additions such as chaff and soaked sugar beet pulp, it is quite easy to change the ratio of hydrolysable (fast release) and fermentable (slow release) carbohydrates in the total diet. Many yards will feed a lower protein diet on a day off, to alter intake against workload—or rather lack of workload. Carbohydrates, or more specifically the balance of carbohydrates, is equally worthy of consideration when adjusting the diet against any change in workload.Starch or Fermentable Carbohydrates?Whilst both are sources of energy and equally valuable to the horse, glucose from starch holds an advantage over VFAs from fermentable carbohydrates when it comes to availability during exercise. Glucose is more metabolically efficient. When working aerobically at slower speeds, glucose is metabolised at nearly twice the rate of VFAs to provide energy to the muscle for contraction. As speed and exertion increases and the horse works anaerobically, the body favours glucose as the energy source over VFAs. As such, starch is always needed in the diet of racehorses and too little starch can negatively impact on performance.The temptation may then exist to push starch intake upwards given its advantages. However, there are several drawbacks to too much starch in the diet aside from over excitability, including increased risk of disorders such as gastric ulceration, colic, tying-up and hindgut acidosis. VFAs derived from fermentable carbohydrates are available as an energy source when working at steadier speeds and contribute to daily energy requirements for basic bodily functions. They should not be discounted as less valuable. Getting the balance right between the two groups of carbohydrates can be a challenge, in which choice of hard feed plays a significant role.Carbohydrate profile of racing feedsHard feed forms by weight, the largest part of a racehorse’s daily intake. The balance of carbohydrate provided through the hard feed will determine the overall balance of the daily intake. Forage, whether hay or haylage, will be a consistent source of fermentable carbohydrate. Hard feeds in contrast are highly variable in the amount of starch vs. fermentable carbohydrate provided.The fibre content of hard feeds is expressed as ‘crude fibre’, and this value can be found on all feed tags. Crude fibre is a laboratory measure that includes most of the cellulose found in the feed but only some of the hemicellulose. It also includes some lignin, an indigestible type of fibre. As such, it is not a true measure of fibre in the feed, but as all horse feeds are required to use this same measure, it allows for comparisons between feeds. Starch can be directly measured and whilst not required to be stated on the feed tag, the majority of feed companies provide this information on their websites or through their nutritional helplines.Example FeedsRacing Feed 1Racing Feed 2Protein g/kg140140Starch g/kg280180Fibre g/kg70130The protein content of a feed has no correlation to the amount of starch or fibre present, and so it cannot be used as a predictor for determining whether the feed is best suited to hard and fast work or to steadier or more stamina-related work. The racing feed 1 example is a cereal-based feed and contains 28% starch (280g/kg), whereas racing feed 2 example contains cereals but in balance with more fibrous fermentable carbohydrate sources such as beet pulp and soya hulls, resulting in an 18% starch value (180g/kg). Fibre content is lower when starch is higher, as seen in racing feed 1, and increases as starch content lowers, as seen in racing feed 2.Both feeds are fortified with the appropriate vitamins and minerals so the choice becomes entirely related to the balance of carbohydrates. Combining feeds, such as the two examples above in different proportions, is often advised when wanting to slowly ‘step up’ or ‘ease off’ horses at various stages of training. Feeds once balanced for vitamins and minerals will not become unbalanced when combined together to give flexibility around the type of carbohydrate needed.SummaryThere are many sources of carbohydrate that form part of the daily diet of horses in training. The site of digestion determines the source of energy produced, either glucose from the small intestine or VFAs from the large intestine. Both sources are needed on a daily basis. The balance between these sources is important as it affects behaviour, digestive health and can reduce the risk of incidence of disorders such as tying-up, colic and hindgut acidosis. By using feeds with different ratios of starch and fibre, it is possible to alter the total daily balance of ‘fast release’ and ‘slow release’ carbohydrates against type of work and stage of fitness. Use of chaff and beet pulp in the feed program also brings flexibility when needing to increase intake of ‘slow release’ fermentable carbohydrates.Reading ListBulmer, L. S., Murray, J. A., Burns, N. M., Garber, A., Wemelsfelder, F., McEwan, N. R., & Hastie, P. M. (2019). High-starch diets alter equine faecal microbiota and increase behavioural reactivity. Scientific Reports, 9(1), 18621.Geor,J.G. Harris,A.P. Coenen,M. (2013) Equine Applied and Clinical Nutrition. London: Elsevier.Hoekstra,K.E. Newman,K. Kennedy,M.A.P. Pagan,J.D (1999). Effects of corn processing on glycemic responses in horses. In: Proc. 16th Equine Nutr. and Physiol. Soc. Symp. pp. 144-148.

By Catherine Rudenko

Carbohydrates are by far the largest component of any horse’s diet, typically two thirds by weight, yet we often focus more on other nutrients, such as protein—which in comparison forms only a small portion of the total diet at around 8-13%. Carbohydrates, specifically the balance between differing carbohydrate sources, influences three key areas relating to performance.

The choice of carbohydrate influences the type of energy available, providing varying proportions of ‘fast release’ or ‘slow release’ energy. The type of carbohydrate chosen also impacts behaviour, increasing or decreasing risk of excitability and certain stereotypical behaviours. Last, but by no means least, the choice of carbohydrate and the way in which it is fed impacts digestive health and the ability of the digestive system to convert food to ‘fuel’ for the body.

Getting the balance right between the different types of carbohydrates is important for getting the right results when having to adjust the intensity of training, when resting a horse and when working back up through the stages of fitness. 

What are carbohydrates? 

There are different ways of classifying or grouping carbohydrates, depending on whether you take things from the plant’s point of view or that of the digestive anatomy of the horse. Working with the horse in mind, carbohydrates are best classified by the section of the digestive system that they are processed in—either the small intestine or large intestine. The site of digestion determines the type of energy provided, often referred to as fast releasing for the small intestine and ‘slow releasing’ for the large intestine. The group of carbohydrates, known as hydrolysable carbohydrates, are the group behind the description of fast releasing, whilst the group known as fermentable carbohydrates are those forming the ‘slow releasing’ category. Within the fermentable group, there are three sub groups of rapid, medium and slow. 

Screenshot+2020-08-07+at+11.25.23.jpg

What are carbohydrates made of? 

There are many types of carbohydrates in the horse’s diet, ranging from simple sugars to more complex structures. They are defined by their degree of polymerisation, which refers to the way in which sugar units are joined together. How a carbohydrate is formed and the type of link present are important as they determine if digestion is possible in the small intestine or whether fermentation in the large intestine is required. This influences the type of energy available. 

For horses in training, the type of carbohydrate of particular interest is the polysaccharide group which includes starch, cellulose, hemicellulose and fructans amongst others. Starch is found in significant quantities in hard feeds, whilst cellulose and hemicellulose, amongst other fermentable carbohydrates are abundant in forages. Pasture is a source of fructans, which can change rapidly depending on growing conditions and daylight hours. 

Structure

Single sugars, also called simple sugars, comprise one unit only. They are categorised as monosaccharides—the most commonly known being glucose. For horses in training this is a highly valuable sugar as it is the main ‘fuel’ for muscles. Glucose forms the basis of many of the more complex structures of interest to horses in training.

When two sugars join together, they are known as a disaccharide—the best known being lactose which is found in mare’s milk. Oligosaccharides refer to more complex structures where more units are joined together—a common example being fructo-oligosaccharide (FOS) which many horses in training are specifically fed as a prebiotic to support digestive function. 

Type of Carbohydrate

Screenshot 2020-08-07 at 11.28.41.png

Polysaccharides, our group of particular interest, are significantly more complex chains that are branched and are not so easily digested as the simple sugars. The branched nature of polysaccharides, such as starch and cellulose, are the result of links between chains of sugars. The type of link present determines whether or not it will be possible for the horse to digest this form of carbohydrate in the small intestine or not.

Starch



Screenshot 2020-08-07 at 11.31.57.png

Starch is the primary carbohydrate of interest in our hard feeds. It is a hydrolysable carbohydrate, which can be digested in the small intestine, releasing glucose into the bloodstream. For horses in training this is the most important fast release energy source. Starch is found in all plants, with the highest quantities seen in cereals such as oats, barley and maize.

Composition of cereals commonly used in racing feeds

Starch is made up of two types of sugar chains: amylose and amylopectin, which are formed from glucose units. Amylose itself is easily digested, however amylopectin has a different type of bond connecting each branch, which the enzymes of the small intestine cannot break down. Feed processing, which changes the structure of starch and breaks apart the previously indigestible bonds, is therefore a key factor in ensuring that when starch is fed that the maximum amount of glucose is derived. 

Amylose and Amylopectin 

Feed processing comes in many forms, from simply crushing or rolling the grain to cooking techniques including micronizing, steam flaking, pelleting or extruding. The amount of processing required for what is deemed efficient digestion differs by grain type. Oats have a natural advantage within the cereal group as they can be fed whole, although processing can still improve digestion. Barley, wheat and maize cannot be fed whole or simply rolled. They require cooking to ensure that starch becomes available, and the impact of cooking processes is much greater for these grains. 

shutterstock_84453238 (2).jpg

The availability of starch is assessed through the amount of glucose released into the blood after feeding. The study below shows the effect of steam cooking maize (corn) compared to two processes that simply change the physical appearance, cracking or grinding. Steam-flaked maize is more available as shown by the greater glucose response. 

Starch is a fast release energy source, being digested in the small intestine, and the term can easily be misunderstood. It does not mean that the horse will suddenly run at top speed nor appear to be fuelled by ‘rocket fuel’. The word ‘fast’ relates to the relatively short time it takes for digestion to occur and glucose to be available. …

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The Balancing Act - feed - supplement

Screenshot 2020-06-12 at 15.34.03.png

By Catherine Rudenko

Key considerations when reviewing what you feed and if you should supplement

With so many feeds and supplements on the market, the feed room can soon take on the appearance of an alchemist’s cupboard. Feeding is of course an artform but one that should be based on sound science. In order to make an informed decision, there are some key questions to ask yourself and your supplier when choosing what ingredients will form your secret to success.

QUESTION #1: What is it?

Get an overview of the products’ intended use and what category of horse they are most suited for. Not every horse in the yard will require supplementing. Whilst one could argue all horses would benefit from any supplement at some level, the real question is do they need it? Where there is a concern or clinical issue, a specific supplement is more likely warranted and is more likely to have an impact. A blanket approach for supplements is really only appropriate where the horses all have the same need (e.g., use of electrolytes).

QUESTION #2: Is it effective?

There are many good reasons to use supplements with an ever-increasing body of research building as to how certain foods, plants or substances can influence both health and performance. Does the feed or supplement you are considering have any evidence in the form of scientific or clinical studies? Whilst the finished product may not—in a branded sense—be researched, the active components or ingredients should be. Ideally, we look for equine-specific research, but often other species are referenced, including humans; and this gives confidence that there is a sound line of thinking behind the use of such ingredients. Having established if there is evidence, the next important question is, does the feed or supplement deliver that ingredient at an effective level? For example, if research shows 10g of glucosamine to be effective in terms of absorption and reaching the joint, does your supplement or feed—when fed at the recommended rate—deliver that amount?

There is of course the cocktail effect to consider, whereby mixing of multiple ingredients to target a problem can reduce the amount of each individual ingredient needed. This is where the product itself is ideally then tested to confirm that the cocktail is indeed effective.

QUESTION #3: How does it fit with my current feeding and supplement program?

All too often a feed or supplement is considered in isolation which can lead to over-supplementing through duplication. Feeds and supplements can contain common materials, (i.e., on occasion there is no need to further supplement or that you can reduce the dose rate of a supplement). Before taking on any supplement, in addition to your current program, you first need to have a good understanding of what is currently being consumed on a per day basis. This is a different matter of comparing one feed tag or supplement pot to another one. Such ‘direct’ comparisons are rarely helpful as dose rates or feeding rates differ, and the manner in which units are expressed is often confusing. Percentages, grams, milligrams and micrograms are all common units of measure used on labeling. The unit chosen can make an inclusion sound significant when perhaps it is not. For example, 1g could be expressed as 1,000mg. Looking at the contribution, any feed or supplement made on an as-fed basis is the only way to know the true value for the horse. There are many categories of supplements in the market with the greatest cross-over existing around use of vitamins or minerals, which appear in both feeds and supplements. Occasionally feeds can also be a source of ingredients used in digestive health supplements or joint supplements. The contribution of your chosen feed(s) is the base from which you decide what, if any, of those matching nutrients or ingredients should be added to. Common areas for cross-over include vitamin E, selenium, B vitamins, iron, magnesium, calcium, phosphorus, zinc and copper. Duplication may also occur around use of vitamin C (antioxidant), FOS (prebiotic), MOS (pathogen binder), yeast (prebiotic) and occasionally maerl (marine algal calcium source).

Vitamins and Minerals An often-seen addition to the feed program for Thoroughbreds are bone supplements—providing relevant minerals such as calcium, phosphorus, zinc and copper. Whilst unquestionably important for sound skeletal development these nutrients are also present in feed, albeit at slightly varying levels by brand. Below is a typical profile of a bone supplement with the information as seen per kilogram on the feed label. Calcium and phosphorus are given as percentages on labels and require converting to grams when looking to calculate the amount of nutrients consumed. In this example, the calcium content is 20%, equivalent to 200g per kilogram.

Screenshot 2020-06-12 at 15.28.34.png

The feeding rate is 31⁄2oz per horse per day. …

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Thoroughbred nutrition past & present

By Catherine Rudenko

Feeding practices for racehorses have changed as nutritional research advances and food is no longer just fuel but a tool for enhancing performance and providing that winning edge. 

While feeding is dominantly considered the content of the feed bucket, which by weight forms the largest part of the horse’s diet, changes in forage quality have also played a role in the changing face of Thoroughbred nutrition. The content of the feed bucket, which is becoming increasingly elaborate with a multitude of supplements to consider, the forages—both long and short chop and even the bedding chosen—all play a part in what is “the feed program.” Comparing feed ingredients of the past against the present provides some interesting insights as to how the industry has changed and will continue to change.

Comparing key profiles of the past and present 

The base of any diet is forage, being the most fundamental need of the horse alongside water. Forage quality and form has changed over the years, particularly since haylage entered the market and growers began to focus specifically on equine. The traditional diet of hay and oats, perhaps combined with mash as needed, provided a significantly different dietary intake to that now seen for horses fed a high-grade haylage and fortified complete feed. 

Traditional Diet

  • 7kg Oats

  • 1kg Mash – comprised of bran, barley, linseed and epsom salt

  • 0.5kg Chaff

  • Hay 6% protein consumed at 1% of bodyweight

Modern Diet – medium-grade haylage

  • 8kg Generic Racing Mix 

  • 0.5kg Alfalfa Chaff

  • 60ml Linseed Oil

  • 60g Salt

  • Haylage 10% protein consumed at 1% of bodyweight

Modern Diet – high-grade haylage



  • 8kg Generic Racing Mix 

  • 0.5kg Alfalfa Chaff

  • 60ml Linseed Oil

  • 60g Salt

  • Haylage 13% protein consumed at 1% of bodyweight

Oats field

The traditional example diet of straights with bran and hay easily met and exceed the required amount of protein providing 138 % equirement. When looking at the diet as a whole, the total protein content of the diet inclusive of forage equates to 9.7%. In comparison, the modern feeding example using a high-grade haylage produces a total diet protein content equivalent to 13.5%. The additional protein—while beneficial to development, muscle recovery and immune support—can become excessive. High intakes of protein against actual need have been noted to affect acid base balance of the blood, effectively lowering blood pH.1 Modern feeds for racing typically contain 13-14% protein, which complement forages of a basic to medium-grade protein content very well; however, when using a high-grade forage, a lower protein feed may be of benefit. Many brands now provide feeds fortified with vitamins and minerals designed for racing but with a lower protein content. 

While the traditional straight-based feeding could easily meet energy and protein requirements, it had many short-falls relating to calcium and phosphorus balance, overall dietary mineral intake and vitamin intake. Modern feeds correct for imbalances and ensure consistent provision of a higher level of nutrition, helping to counterbalance any variation seen within forage. While forage protein content has changed, the mineral profile and its natural variability has not. 

Another point of difference against modern feeds is the starch content. In the example diet, the “bucket feed” is 39% starch—a value that exceeds most modern racing feeds. Had cracked corn been added or a higher inclusion of boiled barley been present, this level would have increased further. Racing feeds today provided a wide range of starch levels ranging from 10% up to the mid-thirties, with feeds in the “middle range” of 18-25% becoming increasingly popular. There are many advantages to balancing starch with other energy sources including gut health, temperament and reducing the risk of tying-up. 

The horse with a digestive anatomy designed for forages has limitations as to how much starch can be effectively processed in the small intestine, where it contributes directly to glucose levels. Undigested starch that moves into the hindgut is a key factor in acidosis and while still digested, the pathway is more complex and not as beneficial as when digested in the small intestine. Through regulating starch intake in feeds, the body can operate more effectively, and energy provided through fibrous sources ensures adequate energy intake for the work required.

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