Encouraging and maintaining appetite

By Catherine Rudenko

Encouraging and maintaining appetite throughout a season 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 behavioural considerations. 

What is a normal appetite? 

Before we can fairly state a particular horse has a poor appetite, we must firstly 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 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 we are dependent on a large amount of grain-based ‘hard feeds,’ which for the majority form 7-9kg of the diet each day. With a potential appetite of 10-15kg 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 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—whilst 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 fibre) 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. 

Analysing 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 fibre—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 synthesise B vitamins in the hindgut. Between these sources a true deficiency rarely exists. Horses with poor appetite are often supplemented with B12 amongst 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, whilst 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. French researchers investigated the behaviour of depressed horses, those determined as non-reactive or with low reaction to stimuli, against their response to sweetened and novel-flavoured foods. The depressed horses consumed significantly less than normal horses (4). There has been much interest in B vitamins for humans with depression as a low level of B vitamins is linked with depressive behaviour (5). Using a B vitamin supplement may also be beneficial to horses. 

Digestive health

Gastric ulceration is commonly associated with changes in appetite (6). Picky eaters may be responding to the physical effect of feed digestion in the stomach. Racing feeds by design contain a significant amount of starch relative to forages, which horses are designed to consume. Starch fermentation in the stomach produces VFAs (volatile fatty acids), which can damage the stomach lining if the pH level of the upper stomach is lower than normal causing discomfort (7). The ability of the upper stomach to remain within normal parameters relates to forage intake. Normal range is pH 5-7, however with limited forage intake the pH can lower to 4. Once below this level, the squamous tissue may ulcerate for a variety of reasons including VFA production at the time of feeding (8).

The incidence level of ulceration in racehorses is high, with reports of 93% of horses having presence of ulcers (9). Not every individual shows the classical symptoms of ulcers but for any horses with poor appetite scoping for ulcers is recommended. The risk factor for development of ulcers is related to the amount of time spent in training, with every week spent increasing risk 1.7 fold (10). A horse with a change in appetite as the season progresses may not just be the result of increasing fitness but an indicator of an ulcer developing. 

Feed flavouring 

The use of flavouring in feed is another consideration for sparking appetite. Although traditionally mint is used as an addition to feed, more recent research into a broad range of flavours has revealed that horses find other flavours more appetising. In order of preference, horse selectively consumed a fenugreek-flavoured cereal by-product first followed by banana, cherry, rosemary, cumin and carrot before reaching peppermint. When added to mineral pellets, the most common item to be left at the bottom of a feed pot when using a coarse mix for racehorses, the inclusions of fenugreek and banana resulted in pellets being more readily consumed (11). Including a novel flavour may be enough to encourage interest in horses that are apparently off their feed for no reason.

Assessment and recommendations for horses with poor appetite

There are multiple factors that influence appetite, and improving appetite will normally require taking more than one approach to get the best result. …

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No guts, no glory!

By Catherine Rudenko

Can we increase the efficiency of the digestive system through dietary and supplementary manipulation in order to alter performance and recovery? 

The idiom ‘no guts, no glory’, when taken in the literal sense, is quite an appropriate thought for the racehorse. The equine gut is a collection of organs, which when in a state of disease, causes a multitude of problems; and when functioning effectively, it is key for conversion of food to fuel and maintaining normal health. 

In the same way we consider how fuel-efficient our car engines are, what power can be delivered and the influence of fuel quality on function, we can consider the horses’ digestive anatomy. The state of the ‘engine’ in the horse is critical to the output. What is fed or supplemented, and the manner in which we do so, has fascinating and somewhat frightening effects on efficiency and recovery. 

We now, in a human context, have a much better understanding of the relationship between the gut and states of disease. Before disease in a notable sense is present, we see loss of function and reduction in performance. With equines, in recent years, the focus has fallen toward ulceration and the stomach. Now interest is growing into the small and large intestines, looking at factors that influence their performance and in turn how this affects performance on the track. 

In order to consider how we can positively influence gut function, first we need to understand its design and capability, or lack of capability which is more often the problem. The horse, by definition, falls into the category of a large non ruminant herbivore—the same grouping as rhinoceroses, gorillas and elephants. The horse is well designed for a fibre-based diet, as reflected by the capacity of the large intestines, yet we must rely heavily on the small intestine when feeding racehorses. Health and function of both small and large intestines are important and are connected. 

Small Intestine 

The small intestine is a relatively short tube of approximately 25m in length—the same length as found in sheep or goats. The primary role of the small intestine is the digestion of protein, fats and carbohydrates. The workload of this organ is significant and is also time constrained, with feed typically moving at a rate of 30cm per minute (1). The rate of passage is highly influenced by whether the stomach was empty before feeding, or if forage has recently been consumed. The advice of feeding chaff with hard feed is in part to the slow rate of passage and give further time for the processes of digestion. 

The mechanisms for digestion in the small intestine include pancreatic juices, bile and enzymes. Of particular interest are the various enzymes responsible for digestion of protein and carbohydrates— the key nutrients often considered when choosing a racing diet. The ability to digest carbohydrate, namely starch, is dependent on two factors: firstly, form of starch and the level of alpha-amylase—a starch-digesting enzyme found in the small intestine. Whilst the horse is quite effective in digestion of protein, there are distinct limitations around digestion of starch. 

Starch digestion, or lack of digestion in the small intestine, is the area of interest. When feeding, the aim is to achieve maximum conversion of starch in the small intestine to simple sugars for absorption. This is beneficial in terms of providing a substrate readily available for use as an energy source and reducing the ill effects seen when undigested starch moves into the next section of the digestive tract. Alpha-amylase is found in very limited supply in the equine small intestine—the amount present being only approximately 5% of that found within a pig. Despite a low content, the horse can effectively digest certain cereal starches, namely oats, quite effectively without processing. However, other grains commonly used, (e.g., barley and maize [corn]), have poor digestibility unless processed. Flaked, pelleted or extruded cereals undergo a change in starch structure enabling the enzyme to operate more effectively. 

Processing grains whilst improving digestion does not alter the amount of enzyme present in the individual. An upper limit exists on starch intake, after which the system is simply overloaded and the workload is beyond the capacity of the naturally present enzymes. The level is estimated at 2g starch per kilogram of bodyweight in each meal fed. In practice, this translates to 3.5kg (7 ¾ lbs) of a traditional grain-based diet of 28% starch. In bowls, this is roughly 2 bowls of cubes or 2 ¼ bowls of mix—an intake typical of an evening feed. The ‘safe limit’ as a concept is questionable because of other factors involved in starch digestion, including how quickly a horse will eat their feed, dental issues and individual variation in the level of alpha-amylase present. 

In practice, feeding racehorses will invariably test the capacity of the small intestine as the volume of feed required to meet the demands of training is significant, and through time constraints of both horse and human results in a large-sized evening meal. The addition of amylase or other enzymes to the diet is therefore of interest. Addition of amylase is documented to increase digestion of maize (corn)—one of the most difficult grains to digest—from 47.3% to 57.5% in equines (2). Equally, wheat digestion has been evidenced to improve with a combination of beta-glucanase, alpha-amylase and xylanase in equines, increasing starch digestion from 95.1% to 99.3% (3).

Use of enzymes in the diet has two areas of benefit: increasing starch conversion and energy availability, and reducing the amount of undigested starch that reaches the hindgut. The efficacy of the small intestine directly impacts the health of the large intestine—both of which influence performance. 

Large Intestine 

The caecum and colon, of which there are four segments, form the group referred to as the hindgut. Their environment and function are entirely different to that of the small intestine. Here, digestion is all about bacterial fermentation of the fibrous structures found in forages and parts of grains and other feed materials. The time taken to digest foodstuffs is also significantly different to that of the small intestine, with an average retention time of 30 hours. 

The end result of fermentation is the production of fatty acids, namely acetate, butyrate and propionate—the other by-product of fermentation being lactate. The level of fatty acids and lactate produced is dependent on the profile of bacteria found within the gut, which in turn react to the type of carbohydrate reaching the hindgut. There are markedly different profiles for horses receiving a mostly fibre-based diet compared to those with a high-grain intake. 

The interaction between the microbial organisms and metabolism, which directly influences health and disease, is gaining greater understanding. By looking at the faecal metabolome, a set of small molecules that can be identified in faecal samples, and the categories of bacteria in the gut, it is possible to investigate the interaction between the individual horse, its diet and bacteria. Of course, the first challenge is to identify what is normal or rather what is typical of a healthy horse so that comparatives can be made. Such work in horses in training, actively racing at the time of the study, has been carried out in Newmarket. 

Microbiome is a term used to describe microorganisms, including bacteria, that are found within a specific environment. In the case of the horses in training, their microbiome was described before and after a period of dietary intervention. The study evidences the effect on the hindgut of including an enzyme supplement, ERME (Enzyme Rich Malt Extract). The table below shows changes in nine bacterial groups before and after supplementation. 

Along with changes in bacterial abundance, which were relatively small, came more significant changes within the metabolome. The small molecules found in the metabolome are primarily acids, alcohols and ketones. Of particular interest, and where statistical significance was found, were changes in acetic acid and propionic acid evidencing an effect on the digestive process. 

Whilst production of fatty acids is desired and a natural outcome of fermentation, further work is needed to determine what is an optimum level of fatty acid production. This study of horses in training is an interesting insight into an area of growing interest. 

Effects on Performance & Large Intestine Function…

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The Balancing Act

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. …

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How the digestion of nutrients may improve horses’ overall condition

By John Hunter

The importance of breeding and training are well established, but there are many differences in the way yards prepare their horses. For several years our group—a trainer, a vet, and a physician specialising in nutrition and the gut—have been working to see if we could improve equine health and performance using a scientific approach.

The aim has been to explore ways in which the biochemistry underlying the digestion of nutrients might improve horses’ overall condition. In some cases this involved applying developments in the field of human nutrition to horses.  In others we have tackled well-established problems within equine physiology. 

Beetroot juice supplementation

Beetroot is a rich source of nitrate and is frequently taken by athletes to improve their performance. Nitrate produces nitric oxide, which dilates blood vessels, thus reducing blood pressure, increasing blood supply and promoting glucose absorption, and potentially increasing the energy available for high-speed exertion. However, not all athletes appear to benefit, and there had been no study so far on the effect of beetroot juice in horses.  

Twenty racehorses (colts and geldings) in full training were divided into two groups. All were fed their standard diets. One group received beetroot juice with a sweetener to mask the taste and the other a sweetener only for four weeks. After four weeks, nitrate levels in the blood were measured and compared to the starting levels. The level of nitrate rose very slightly in the test group, but no change in performance or condition was noted in any of the horses. Beetroot juice does not seem to help horses.

Vitamin B12

Vitamin B12 is important, not only for preventing anaemia and maintaining the health of the nervous system, but also because it produces enzymes which are crucial for allowing the entry of nutrients into the biochemical cycles producing the main source of energy in both man and horse: ATP. In humans, B12 is derived from eating meat, fish and dairy products. Horses and other herbivores, obtain their vitamin B12 by ingestion of cobalt from pasture which is then used by intestinal microorganisms to form the vitamin. As racehorses are rarely turned out on pasture, most feed concentrates are supplemented with B12.

‘As the intensity of work increases, the composition of the diet and the amount of food consumed change as a consequence of the increased consumption of starchy cereal grains. This will alter not only the dietary supply of B vitamins but also the intestinal synthesis…and it is an open question whether the rate of their absorption is exceeded by tissue demand when horses are in intensive training’ (Frape 2010, p250).

The amount of soluble carbohydrate in the diet of the racehorse must be carefully regulated. ‘Racehorses on a high-concentrate/low-roughage diet and little access to grazing are to some degree already on a metabolic knife-edge’ (Ramzan, 2014, p258).

The trainer was concerned that a number of horses in his yard were below par from the start of the Flat season as their appearance and performance were disappointing. Their diet was unchanged, but they ate poorly and failed to regain weight after racing. Veterinary investigations, including full blood screening, failed to reveal any cause.

As lethargy and early fatigue are two of the earliest symptoms of B12 deficiency in man, it was decided also to check the B12 status of the horses affected. Twenty racehorses, which were out of condition, were identified and divided into two groups. Blood samples were taken, and B12 levels were recorded.  One group was supplemented with B12 injections at 3mg twice weekly for three weeks (18mg in total). The other group acted as controls. At the end of that time, the horses’ condition was reassessed by the trainer on his return from a week’s absence.

The concentration of vitamin B12 in the 20 horses was found to lie within the normal range and was slightly greater than that found in healthy yearlings on pasture at a local stud. After B12 injections, the level rose significantly. A further determination later in the season showed that this initial increase had disappeared. Overall there was no difference between the blood levels of B12 at the end of season compared to the beginning. Changes in B12 concentration, however, did not affect performance. The trainer, who was not informed which horses had received B12 supplements, considered that 8 horses had improved and 12 had not. These were equally distributed between the two treatment groups, and those considered to have improved did not have higher levels of B12.

Thus, despite previous anxieties, racehorses on standard diets have normal B12 levels which remain satisfactory throughout the season. Supplementary injections increase blood concentrations temporarily, but there was no correlation between blood B12 concentration and performance.

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How has horses' feed changed? 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. 

Whilst 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

The traditional example diet of straights with bran and hay easily met and exceed the required amount of protein providing 138% of requirement. 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 whilst 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. 

Whilst 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. Whilst 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 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 whilst 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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All tied up?

By Catherine Rudenko

Tying-up or ER (exertional rhabdomyolysis) is a problem that every yard will encounter at some point in time with reports of 5-7% of the thoroughbred population being affected. ER is the general term used to cover two main forms of tying-up, acute or recurrent. ER by definition relates to the breakdown of striated muscle fibres following exercise. These fibres connect to the bone allowing movement of the skeleton. Damage causes anything from mild stiffness to the inability to move.

With much still unknown about the condition, the focus falls on reducing risk and ongoing management of those affected with recurrent form. The main area for intervention and management relates to feeds and feeding practices, an area that can be directly controlled by the yard and adjusted as needed for the individuals most affected.

Acute Exertional Rhabdomyolysis

The acute form is typically caused through factors external to the muscle rather than their being an intrinsic muscle defect.

Most commonly seen when the horse is adapting to a new level of work and the intensity or duration is too strenuous. Where speed work is concerned, the most likely cause is a depletion of cellular high energy phosphates, the muscles’ energy supply, combined with lactic acidosis. Where endurance work is concerned, depletion of intracellular glycogen—the stored form of glucose often combined with over-heating and electrolyte imbalances—is the common cause.

The other key factor for an acute episode is dietary energy intake being excessive to the current level of work. The use of high starch feeds to supply energy for horses in training is a common practice with grains, traditionally oats, forming the basis of such feeds. In the early stages of fitness work, an over-supply of energy relative to need, particularly when starch forms a large part of the diet, is a risk factor.

Recurrent Exertional Rhabdomyolysis

This form of ER, where episodes are frequent and often seen even at low levels of exercise, has led to the suggestion that much like humans, there is an inherited intrinsic muscle defect. Such defects would predispose the horse to ER. Documented defects relevant to thoroughbreds include a disorder in muscle contractility or excitation contraction coupling, whereby muscle fibres become over-sensitive and normal function is disrupted.  

Risk factors for ER in horses with the recurrent form include stress or high excitement during exercise, periods of jogging (10-30 minutes), infrequent exercise and over-feeding of energy in a high starch format relative to need.

Dietary Considerations for ER

The amount of energy fed and the type of energy fed are important considerations whether looking to avoid an acute feed related episode or considering the management of a horse with the recurrent form.

Other nutrients often talked about when managing ER include vitamin E, selenium and electrolytes. Historically the inclusion of vitamin E and selenium were considered important for the prevention of further episodes, however there is no evidence to support such use. A case of deficiency in either of these nutrients may well put the horse at a disadvantage and could perhaps create a state where occurrence is more notable; however, with the advent of fortified and balanced complete bagged feeds, such nutrients are normally supplied in more than adequate amounts. Their role as antioxidants which function to ‘mop-up’ damaging free radicals generated through training is where their use can benefit any horse at this level of work. The use of additional vitamin E is also recommended when increasing the fat content of the diet—a common practice when feeding horses with recurrent ER.

Electrolytes do play an important role in normal muscle function, and any deficiency noted in the diet should be corrected. Identifying a need in the diet is more easily done than determining if the individual horse has a problem with absorption or utilisation of the electrolytes. A urinary fractional excretion test (FE) will highlight issues, and subsequent correction through the diet to return the horse to within normal ranges may offer some improvement. However, it is important to note that for horses with recurrent ER, where an intrinsic muscle defect is present, the research to date has shown no electrolyte imbalances or differences between such horses and unaffected horses.

Quantifying ‘Low Starch and High fat’ Feeding

The recommended practice for management of ER is a reduction in starch and an increase in fats. This practice has two ways of benefiting the horse: a reduction in ‘spookiness’ or reactivity and a positive effect on muscle damage as seen by lower CK (creatine kinase) levels following exercise.

Positive effects on lowering CK levels were found when a higher proportion of the energy fed came from diets higher in fats and lower in non-structural carbohydrates (starches and sugars). The effect was noted when fed at 4.5kg/day—an amount easily reached and normally surpassed when feeding horses in training. The beneficial diet provided 20% of energy from fats and only 9% from starches and sugars compared to the more traditional sweet feed diet providing 45% of energy from starches and sugars and less than 5% from fats.

Finding Fats

Top dressing of oils will increase fat in the diet - with a normal intake of up to 100 mls per day. Although the horse can digest higher amounts, palatability usually restricts a higher intake. Pelleted or extruded fat sources are increasingly popular as alternatives to oils for their convenience of feeding and palatability. Straight rice bran and blends of materials such as rice bran, linseed and soya are available from most major feed companies. Oil content will typically range from 18-26% providing 180g-260g of oil per kilogram as fed.  

Racing feeds will also provide oil in the diet; content is quite varied typically from 4-10% providing 40g-100g per kilogram as fed. Hay and haylage also contains oil at a low level, typically 2% providing just 20g per kilogram on a dry matter basis.

Choosing Carbohydrates

Traditional feeding based on oats and other whole grains will have a higher starch content than feeds using a combination of grains and fibres. Levels of starch found in complete feeds and straights have a broad range from as low as 8% in a complete feed, specifically formulated to have a low starch content, and up to in excess of 50% for straights such as barley and naked oats.

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The importance of good nutrition and its bearing on mental health

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 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 National Hunt jockey in his younger days.

“For my first ride as a conditional jockey at Southwell in 1985, I lost a stone in five days to make 10st (63.50 kg) 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 athletes and 9st, (57.15 kg), 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.

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“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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Feeding for Weaning Success

By Dr. Emma Hardy, PhD

The first 12 months in the life of a foal are pivotal in building the foundations for overall long-term health and optimal development. It is also during this initial year that the foal will face its first major life event in being weaned from his dam, and he must cope with the nutritional challenges this may bring.

There are many approaches to weaning and every breeder strives to make the right choices for the best outcome. The reproductive status of the mare, the cost and time available, the plans for the foal, and the physical practicalities of the yard will often dictate which type of weaning strategy should be employed. They all come with their own benefits and drawbacks.  Choosing the correct feeding and nutrition programme is key to your success.

Early growth

The dam’s milk is nutritionally complete, providing all the energy and nutrients required for a foal. However, at around three months of age, milk yield peaks, then naturally starts to decline, along with suckling frequency. At the same time the foal increases its intake of non-milk feedstuff such as grass, forage, and some concentrates as the his nutritional needs begin to overtake the mare’s own supply. This period coincides with rapid weight gain, with foals reaching around 30% of their adult weight by this point.

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Genetics, breed, seasonal temperature differences, and nutrient availability will all contribute to the growth rate of the foal. Small fluctuations in growth rates are normal and nothing to worry about. However, continuing or significant deviations from the National Research Council (NRC) 2007 growth recommendations can predispose the foal to health issues, most notably orthopaedic problems.  The structures and tissues of the foal’s body do not grow at the same rate: bone matures earliest, followed by muscle and then fat. Indeed at 12 months of age the yearling will have attained 90% of his mature adult height, which emphasises the importance of correct diet in supporting this rapid early bone growth.

Introducing creep feed

Although the foal supplements his milk intake with small quantities of the dam’s feed and forage, the introduction of a creep feed prior to weaning can help sustain normal growth rates. Highly digestible creep feed is formulated from milk proteins and micronised grain, and it’s fortified with vitamins and minerals. In addition to encouraging growth, it promotes gastrointestinal adaptation to the post-weaning diet and is also described as a significant factor in the reduction of weaning-associated stress.

The appropriate age to introduce a creep feed depends on many factors. For the foal at pasture and doing well, there should be little need for any additional nutrition until two-to-three months of age, when milk supply begins to diminish. Earlier intervention may be necessary should the foal be orphaned or fail to thrive due to inadequate milk supply or other environmental influences.

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From Fertility to Foal: considerations for digestive tract health

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

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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.

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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.    

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The Positive and Negative Effects of Oil in Equine Nutrition

Published in European Trainer, January - March 2018, issue 60.

Oil is a regular addition to modern racing diets, either by feeding a high oil-containing racing feed or through extra addition of liquid vegetable oil. Research over the years has shown that oil is palatable to horses and digested very well, and that there is little difference in digestibility between the main types of vegetable-based oils used.

Oil that is integral to feed ingredients, such as that found in rice bran, linseed, naked oats, soya, etc., may have a marginally lower digestibility, as this will depend on how digestible the encapsulating matrix is to the horse. However, in the main both free oil and integral oil is well tolerated and digested in horses.  

In a natural environment, horses can easily consume between 2-3% of their body weight as dry matter from pasture. Oil has always been a natural part of the horse's diet, as grass contains about 2-3%, which may seem low but can provide the equivalent of 200-400mls of oil per day. Other forages, such as hay, haylage, and chaff, will also contain oil at a similar level on a dry matter basis.  

Horses can tolerate up to 20-25% of their total energy intake coming from oil, and this has been exploited successfully....

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Is EIPH beyond the scope of dietary change?

Published in European Trainer - October - December 2017, issue 59.

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Exercise induced pulmonary haemorrhage has been a concern to trainers for a very long time. The historic record of EIPH in horses such as ‘Bleeding Childers’, a son of the Darley Arabian, a founder of the modern thoroughbred, shows that ‘bleeding’ as it is commonly known is an age-old problem.

The prevalence of EIPH during high intensity exercise,  such as racing, is relatively high, but influenced greatly by how it is diagnosed. For example, the prevalence of EIPH is quite low when the appearance of blood from the nostrils (epistaxis) is used as the diagnostic criteria. Unsurprisingly, it is much higher when more rigorous investigative techniques such as endoscopy or bronchioalveolar lavage are used.  Additionally, the prevalence increases when horses are repeatedly examined. In clinical terms, it has been suggested that if you look hard enough diagnostically, and often enough, almost all horses will show a degree of EIPH with racing at some time.  A large Australian study has also reported that there is a proven heritability or genetic element to this condition.

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Notwithstanding this, EIPH presents a major concern for horses in training, as it often leads to loss in training days and may impact on race performance, although this seems to be dependent on the degree or grade of EIPH involved. A period of absence from the racecourse can also be a requirement of some racing jurisdictions, e.g. the British Horseracing Authority in the UK, following epistaxis, where blood is seen visually from one or both nostrils. Public perception is also relevant, especially when the public mood puts racing under tighter scrutiny in terms of animal welfare.

There is also a mood for change with regards to the previously widespread use of pre-race medications such as furosemide (which has been widely used to treat EIPH) in countries such as the USA.  The HH Sheikh Mansoor Bin Zayed Al Nahyan Global Arabian Horse Flat Racing Festival had recently announced that its races in the US will be ‘lasix-free’, which has been widely welcomed by trainers worldwide.

In some racing jurisdictions, nasal strips can be used which support the tissues of the nasal cavity helping to keep the upper airway fully open during exercise.

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Does nutrition factor in injury, repair and recovery?

First published in European Trainer issue 58 - July - September 2017

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Lost training days through injury or infection are problematic for trainers, both practically and commercially. It is a stark fact that 50% of thoroughbred foals, bred to race, may never reach the racecourse.

Lost training days through injury or infection are problematic for trainers, both practically and commercially. It is a stark fact that 50% of thoroughbred foals, bred to race, may never reach the racecourse.  In young thoroughbreds, musculoskeletal problems have been cited as the most common reason for failure to race and this appears to continue to be a major issue for horses in training.  

An early study carried out in 1985 in the UK reported that lameness was the single biggest contributor to lost days of training, and subsequent research 20 years later found that this was still the case, with stress fractures, which involve normal bone being exposed to abnormal stress, being cited as a significant underlying cause.  Perhaps not surprisingly, two-year-olds were more susceptible to injury than three-year-olds.  Whilst there are of course many other reasons – including muscular issues such as tying up, respiratory problems, and viral infection – why horses may fail to train, in this survey medical issues accounted for only 5% of the total training days lost.

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No foot no horse - the influence of diet on the hoof

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First published in European Trainer issue 57 - April '17 - June '17

Metabolomics - The key to understanding equine gut health

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Marginal Gains - can the philosophy apply to horseracing?

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Equine Metabolic Syndrome

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Trickle feeding - more in tune with nature

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North American version: issue 35 February- April 2015

European version: issue 48 January- March 2015

Prohibited natural substances - The risks and responsibilities

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The challenge of feeding globetrotting horses

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THIS ARTICLE FIRST APPEARED IN EUROPEAN TRAINER - ISSUE 46