Over the last 20 years, research in many countries has provided much more information on the exercise demands and nutrient requirements of racing and exercising horses. Much of this work has been carried out on Standardbred racehorses because of their availability, temperament and disciplined training.

The significant differences in the diets and training programs of Standardbreds in comparison to Thoroughbred racehorses include:

• On average, a Standardbred horse in training exerts 12 times more effort in distance and time spent training than a Thoroughbred horse. Standardbreds race on average 3 times more frequently and require an overall higher standard of conditioning and fitness. They often race and remain competitive until they are 7 years of age or older.
• Many Standardbreds are smaller framed horses, which combined with the physical stress and fatigue of long, hard training, reduces their appetite and capacity to consume large bulky feeds.
• In order to achieve the level of fitness required in Standardbreds, they are often conditioned on alternate days by 20-30 minutes of jogging and regular speed work in hopples, which increases sweat output, electrolyte depletion and risk of dehydration, especially during hot weather.

In Australia, a survey was carried out by Dr. Louise Southwood and colleagues in 1993 which compared the feeding practices of thoroughbred and Standardbred horses in training.

In this paper, I will discuss some of the practical aspects of feeding Standardbreds. A Standardbred horse in training will normally be able to consume 2.25-2.5% of its body weight daily in a 60-65% concentrate to 35-40% roughage mix.

The most important nutrient, besides water, is an adequate supply of energy, provided in a form that is palatable and accepted, well utilised, and in a volume or bulk that can be consumed by a horse in hard training.

Traditionally, diets for Standardbreds in training were based on oats and protein meals or seeds, with roughages provided by hay and chaff (chopped hay) and limited access to pasture.

Many Standardbreds are small framed with a limited appetite capacity, which is often further depressed by high grain diets and the stress associated with hard training.

In order to meet energy needs based on oats as the major energy source, up to 6-7 kg of oats has to be provided in a total of 11.0-12.0kg of dry ration each day. Many part-time trainers are only able to feed twice daily, which increases the risk of overloading oats in the bulk of the meal that has to be consumed in each feed.

Oat starch is well digested in the small intestine, ranging from 70-90% when volumes up to 5 litres (about 2.5kg) are given in each meal. Higher intakes of highly fermentable starch in each meal can result in reduced starch digestion in the small intestine, with overload of raw (uncooked) oats into the large intestine. Excess starch fermented in the large intestine leads to the production of D-lactic acid, which increases the acid level within the hindgut, developing what is termed a "hindgut acidosis". A more acid hindgut limits subsequent fermentation and reduces the digestion of other fibre. Hindgut acidosis results in the passage of soft, moist manure with an increased water content, ‘pasty’ consistency and ‘sour’ odour, often referred to as ‘cow pat’ droppings

The amount of oats can be reduced and replaced with lower volumes of more energy-dense cracked corn or rolled barley as energy boosters to a basic oat based ration to meet the increased needs of advanced training and regular hobbled-up workouts. However, the risk of starch overload can be increased with the reduced digestion of raw corn starch (30%) and raw barley (23%) in the small intestine if more than 2.5kg of total grain is fed in each meal.

Substituting some of the oats with cracked corn, rolled barley, cracked lupins and sunflower seeds can reduce the volume or bulk of the meal that has to be consumed. Lupins and sunflower seeds do not contain starch with the energy being provided by fat (oil), protein and fermentation of fibre. The volumes of these feeds must be limited to 25-30% of the total grain intake for lupins, and 15-20% for sunflower seeds to ensure best acceptance and utilisation and avoid overload of protein. Reducing the volume of the feed in this way helps smaller framed horses or those with loss of appetite or ‘picky feeding’ habits in hard training to eat enough to meet their needs.

The recent availability of extruded (pressure cooked) corn, barley and lupins, expanded or micronised (heat treated) grains, and the use of vegetable oils as a source of high energy density fat, can provide some practical alternatives to the problem associated with high oat and raw grain intakes.

The extrusion (pressure cooking) process opens up (expands or gelatinises) the densely packed raw starch granules to provide porous particles that are more efficiently attacked by enzymes in the small intestine. It is difficult to extrude oats because of its high fibre content. In addition, there is no advantage to be gained from extruding oats, which are reasonably well digested in the small intestine in amounts of up to 2.5kg per feed.

Boiling barley, which is a time consuming process, increases its starch digestibility to around 50%, which is a significant improvement over the raw grain (23%).

The extrusion (cooking) of corn increases its starch digestibility in the small intestine from around 30% to 90% and barley from 23% to around 65%.

Controlled extrusion also improves the digestibility of protein by removing toxic factors, and increases the amino acid availability in protein grains, such as soyabeans, lupins and tick (faba or horse) beans, with better acceptance, palatability and storage life.

Extrusion of corn and barley, or using a feed with an extruded base of these grains, significantly reduces the risk of hindgut acidosis and its associated problems of ‘hyper’ behaviour, pasty ‘sour’ droppings and foot soreness.

Extruded grains are regarded as ‘cool’ feeds as horses are less likely to develop ‘hyper’, hard to handle, behaviour if a proportion of the starch is primarily digested in the small intestine. However, extrusion changes the texture of the grain, and some horses will not readily accept extruded rations, so a stepwise introduction over 10-14 days is usually required when introducing extruded grains to the ration.

Although extrusion adds a cost to the price of the readily available raw grain, the improved digestibility may enable from 30-35% less weight of extruded grain to be fed for an equal energy benefit to that provided by raw (uncooked) grain.

Vegetable oils, as a source of fat, such as corn oil, sunflower oil, canola oil, blended cooking oils and commercial oil blends with higher Omega-3 fatty acids are becoming more widely recognised as alternative energy dense sources used as a part substitute for high starch rations based on grains in the diets of hard working horses, such as Standardbreds in advanced training. Horses can utilise fats during conditioning aerobic training, and in time, increase muscle glycogen (energy) and conserve these stores for metabolism during faster workouts and racing.

Most oat and cereal based concentrates contain 2-5% fat, but horses, once conditioned to accept and digest fat by a stepwise introduction over 10-14 days, can utilise a concentrate ration containing up to 8-10% fat by weight.

Substituting some of the raw grain with vegetable oil has some distinct advantages in hard working horses. These include:

• Fat is energy dense. One cupful (250mL) of vegetable oil has the same amount of energy as 750g (about 1 ½ litres volume) of oats, 600g rolled barley (about 1.2 litres volume) and 550g cracked corn (about 750mL volume). When introduced using a stepwise substitution in 50mL increments at 3-4 day intervals over 10-14 days, up to one cupful of oil can be fed morning and evening. On an energy basis, 500mL fat daily can substitute for 1 ½ kg (about 3 litres) of oats and significantly reduce the bulk of concentrate ration a horse in hard work with a depressed appetite has to consume.

Substituting oats with fat as oil is an advantage in smaller framed horses with a limited gut capacity. Fat is a ‘cool’ source of energy as it is digested primarily in the small intestine, reducing the ‘hyper’ behaviour caused by starch overload into the hindgut. Replacing 1 ½ kg (3 litres) of oats with equivalent energy in 500mL oil, can also reduce hindgut weight by 4-5kg, which can increase speed and race performance of horses racing over 1600 metres or a longer distance.

• Fat also reduces the ‘heat waste’ during fermentation of overloaded starch and protein in the large intestine of horses, which makes it an ideal energy source for heavily sweating, hard working Standardbreds, especially during hot weather.

Around 30% of the total energy in oats is converted to heat waste during hindgut fermentation of its fibre and overloaded starch. Less fibrous grains, such as corn and barley, have a lower heat waste of around 20%, but retain the problem of hindgut acidosis if overloaded into the hindgut. Extruded grains, such as cooked corn and barley, produce 10-12% heat waste, but fat has virtually no heat waste as it is not fermented in the hindgut.

• When fat is substituted for grain in a diet, it is a good practice to supplement with Vitamin E up to 1000 iu daily to assist the aerobic use of fat, or preferably a Vitamin E – selenium supplement. In practice, feeding supplementary fat, extruded grains, Vitamin E and electrolytes with potassium and magnesium may reduce the risk of tying-up in fillies and mares.

Although fat adds from 15-20% to the cost of each unit of energy provided by oats or other grains, its benefits often outweigh the additional cost of the oil.

It is most economic to purchase oils in bulk 20 litre containers or 200 litre drums. Although corn oil has been regarded as the most palatable, well accepted and utilised by horses, it contains a low level (2%) of Omega-3 fatty acids. These provide natural tissue and joint anti-inflammatory compounds (called eicosanoids) and hormone action to improve the function and strength of blood vessels and muscle cell walls. Corn oil is also subject to oxidation or the development of rancidity during storage once the full container is opened, which reduces its palatability and utilisation as a source of energy.

Sunflower oils and blended oils contain 1% or less of Omega-3 fatty acids. Linseed oil contains 57% Omega-3 fat, but excess Omega-3 intake can imbalance the function of Omega-6 and other fatty acids.

Commercial blends of oils boosted with Omega-3 fats are available and contain anti-oxidants to reduce rancidity and improve stability of the fats.

Cold-pressed canola oil (10% Omega-3, 20% Omega-6 fatty acids) is a highly palatable source of these essential fats in a balanced ratio and, being a monounsaturated fatty acid mixture, is less likely to oxidise and turn rancid if stored in a cool area. Amounts of 250mL (1 cupful) of canola oil can be slowly introduced to the ration in each morning and evening feed as an energy substitute for oats and other grains.

• Fats as liquid (vegetable) oils help reduce dust and separation of fines in the feed, but they must be carefully mixed into the feed in small amounts at a time to prevent them coating the feed bins with a thick oily residue that can turn rancid.

Horses have to obtain their protein needs as individual amino acids following digestion of crude protein in the small intestine. Very little, if any, food protein or microbial protein from bacterial flora is available from the hindgut of the horse. Although 50% of the amino acid content of protein can be used as a source of energy, protein is a less efficient form of energy and more expensive than the equivalent amount of energy liberated by starch, fat or fermentation of fibre.

The survey by Dr. Louise Southwood and co-workers indicated that Standardbred horses in training were fed 12-24% more protein in their rations than recommended by recognised guidelines in the NRC (1989) publication. Many Standardbred trainers consider a horse will perform more consistently on a 12-14% crude protein ration, but often the protein intake is elevated by the routine, but often unnecessary, addition of oil seed meals as protein supplements on lucerne based diets. Diets containing more than 40% (about 3kg) of the roughage as lucerne hay and chaff daily with a grain based concentrate usually provide adequate protein.

Excess crude protein not digested in the small intestine is overloaded into the large intestine, where it is fermented to amino acids with production of ‘heat waste’, which is 6 times higher than the amount released during the fermentation of starch and other carbohydrates.

Crude protein intakes in excess of 50% of a horse’s daily needs can result in increased heat production during fermentation, which adds to the heat load a working horse has to dissipate, especially during hot weather. An excess intake of protein has been associated with elevated heart and respiratory rates. This is often manifested by ‘blowing’ from the lungs after hard exercise as retained heat is unloaded via the respiratory system, and a less than optimum race performance.

Young horses in training that are less than 3 years old, horses in lighter condition or those with a poorly developed muscle mass, may benefit from an additional 2% crude protein (CP) provided by 450g (2 cups) soyabean meal (44.5% CP), or alternatively 530g (3 cups) of canola meal (36%CP), or alternatively 720g (6 cups) or sunflower seeds, or alternatively 720g (4 cups) of crushed tick beans (faba or horse beans) added to their diet daily or the first 6-8 weeks of training. Soyabean and canola meal have a higher lysine and other amino acid content for tissue growth than the other common protein sources.

An adequate intake of fibre of around 0.75-1.0% body weight, or between 35-45% roughage by weight as chaff and hay, must be provided when horses are being fed a high grain ration to meet energy needs. Normally, providing more than 3kg of alfalfa (lucerne) hay or chaff satisfies the protein and calcium needs of a horse fed on a grain concentrate or sweet feed. During hot weather, the fibre content can be reduced to 0.5-0.75% body weight to minimise heat production during digestion, whilst still retaining water holding capacity in the hindgut as a reservoir against dehydration. Only good quality hay, free from moulds and minimal dust should be used, as hay is the most common source of allergic moulds that can significantly affect airway function and reduce race performance.

The traditional high energy, grain based diet is relatively deficient in calcium, iron, copper, manganese and selenium. It is estimated that a horse in training requires at least 40g of elemental calcium daily. Adequate calcium is required for growth and continuous remodelling of bone to maintain maximum skeletal strength during periods of strenuous exercise and in Standardbreds to replace sweat loss of calcium during conditioning work. Grains contain from 3 to 20 times more phosphorus than calcium. A deficiency or imbalance of calcium in the diet may result in lameness problems and unsoundness, particularly in young, growing horses in their first preparation. Most horses on diets containing phytic acid, such as high grain or an intake of bran greater than 1 litre per 100kg body weight daily or those fed on tropical grass roughage have a deficiency of calcium due to oxalate binding of calcium by the grass.

A survey in Hong Kong suggested that daily supplementation of high grain rations with 60g of calcium powder, providing 24g of calcium, reduced the incidence of spinal bone problems by 35% in racehorses on high grain rations.

Alfalfa (lucerne) and clover hays contain a much higher calcium content relative to grains. However, a horse may not be able to eat a sufficient volume of bulk as hay to balance the ration when consuming up to 6.0-7.0kg of grain to meet energy needs.

As calcium is lost in sweat, (300mg calcium/1 litre of sweat) extra calcium should be added to the diet of heavily sweating horses, particularly those training under hot, humid tropical conditions. Horses on a high grain diet should be provided with a calcium supplement or a sweet feed containing at least 1% calcium each day to meet calcium needs.

Cereal grain based diets contain low levels of Vitamin A (as carotene), Vitamin D, Vitamin E and many B-Group vitamins. The natural content of vitamins can be depleted during harvest, processing and storage of grain. Horses under the stress of training are less able to efficiently convert carotene in hay and grain to Vitamin A (retinol).

Storage of grains and hay results in destruction of up to 80% of the potential Vitamin A activity over a 3-6 month period. Adequate Vitamin A is also required to maintain the blood count and overall performance.

Observations in racehorses suggest that daily intakes of 50,000iu of Vitamin A reduced the incidence of tendon weakness and breakdown in horses fed on cereal grain based diets.

Restricted or lack of opportunity for day-time grazing, limits the natural synthesis of Vitamin D from sunlight on the skin.

Although adequate Vitamin D for a horse in training would be provided by about 3-3½kg of quality sun-cured alfalfa (lucerne) hay and chaff daily, intakes below this level to avoid excess bulk, may not provide sufficient Vitamin D to meet the requirements of a stabled horse on a high phosphorus, low calcium diet. A supplement of calcium to provide 3000iu of Vitamin D or a ‘sweet’ feed containing extra vitamin D is recommended.

Vitamin E is relatively deficient in grains and losses of up to 50% or more occur up to the time grains and hays are harvested and stored as feed. Studies in Sweden indicated that supplementary Vitamin E (600-1800iu daily) is required to maintain normal blood, liver and muscle levels in Standardbred horses fed on cereal grain and hay based diets in training.

The NRC (1989) guidelines for working horses suggest that 1000iu of Vitamin E daily should be provided in the ration.

Many of the B-Group vitamins are required for efficient energy metabolism and blood formation. It is considered that horses in work on high grain, low fibre diets, may not be able to synthesise and absorb adequate amounts of the B-Group vitamins, produced by bacterial fermentation in the large intestine, to meet the elevated needs required for energy utilisation during fast exercise.

Horses in work on grain based rations with inherently low levels of natural B-Group vitamins will often benefit from B-Group supplementation.

Recent observations indicate that supplementary B-group vitamins help maintain appetite, particularly following hard exercise or racing, delaying the onset of track sourness and weight loss in racehorses during long term training. Daily supplementation of 1000-2000m g Vitamin B12 in the feed of horses on high grain diets with low-grade hindgut acidosis may help improve the appetite. However, feeding to reduce raw starch overload into the hindgut will reduce the other side effects of hindgut acidosis.

Studies have indicated that the provision of adequate water and a daily intake of electrolytes helps prevent dehydration, maintains the appetite and performance in racing horses.

Conditioning a Standardbred horse by jogging for extended periods of 30-40 minutes daily under hot, humid conditions will result in a sweat loss of 15-20 litres daily, or even higher volumes of 10-11 litres per hour during very hot weather. High sweat losses of potassium and chloride salts daily over a 3-4 week period, can result in an elevation of bicarbonate or alkaline levels in the blood, referred to as ‘hypochloraemic alkalosis’ due to excess chloride loss. Elevated blood alkaline levels may eventually lead to symptoms of thickwindedness or ‘blowing’ during and after hard exercise, often commonly referred to as being ‘fat inside’. When extra work is given to overcome the ‘fat inside’ condition, the heavier sweat loss results in prolonged ‘blowing’ after exercise although it is not due to excessive fat in the gut, lungs or around the heart. More severely affected horses become ‘spooky’ and may shadow jump, and are also more likely to break at the barrier. Daily supplementation with a high potassium electrolyte mix containing at least 20% potassium and 30% chloride will help to correct and prevent the alkalosis condition.

During early training under cool conditions, a supplement of 45-60g (3-4 tablespoons) of salt (sodium chloride) will normally meet electrolyte needs of a horse on a standard grain and hay diet. A horse that is nervy, or sweats heavily during conditioning work or hot weather, will benefit from additional potassium and chloride salts.

It is essential that the dietary intake relative to the amount of exercise is maintained during the 2-3 days prior to racing, especially when the intensity of exercise is tapered off. There is no benefit obtained by manipulating the diet to increase the energy intake by carbohydrate loading in preparation for racing, as it may lead to digestive upset and metabolic conditions such as tying-up in horses.

Observations suggest that increasing the grain intake by 10% in the total feed, or about 1kg of grain mix daily and reducing the hay and chaff by 500g daily for 2-3 days before racing and for 1-2 days afterwards may aid performance in races between 1600 to 3000 metres. This slight change in diet proportions can reduce gut weight by 3-4kg within 2-3 days and may make heavier build horses more competitive. Feeding a 50:50 grain and chaff mix by volume on the night before and morning of a race will help reduce gut weight. However, care must be taken to avoid grain overload and risk of excess acid production in the large intestine. Adequate fibre to retain fluid and maintain digestive function must be provided, whilst limiting gut weight in the 2-3 days prior to racing, especially under hot, humid conditions.

The dehydration state should be assessed at least 72 hours prior to racing, especially during hot weather or if a horse has to travel a long distance to race. Supplementation with routine electrolytes in the feed, and additional fluids, such as twice daily doses of a rehydration fluid over the tongue, with free access to water, will aid in restoring fluid balance over the 48 to 72 hours prior to racing. If a horse is severely dehydrated with a ‘tucked up in the belly’ appearance, a saline drench may be administered by stomach tube at least 48 hours prior to racing to allow time for restoring fluid balance. Note:- Maximum concentration of a saline drench should not exceed 20g of salt mix per litre of water, in a minimum of 4-5 litres of water. Free access to water must be provided after administering saline drenches. In most cases, saline drenches are not required if a specialised rehydration fluid is administered by syringe over the tongue twice daily during the 48-72 hour period prior to racing.

There are no established recommendations for feeding horses on raceday. Generally, a horse should be given its last grain based feed 6-8 hours before racing, and provided with a limited amount of dampened roughage up until travelling to the racetrack.

Oral dosage of B-group vitamins given 4-6 hours prior to racing may help maintain the appetite following hard work or racing. In a nervy horse, recommendations for use of high dose of Vitamins B1 and/or Vitamin E may also be adopted on raceday.

Although it is traditional to withhold water for up to 6 hours prior to racing to limit gut weight under hot conditions, water should be provided to replace sweat loss up until the horse is stabled at the track. If a horse is nervy and ‘sweats up’ during travelling, a rehydration fluid can be given over the tongue on arrival at the track, along with 2-3 litres of water to drink to assist in restoring electrolyte and fluid levels immediately prior to a race.

The following guidelines may assist in recovery after racing:-

1. If a horse is to continue in normal work after a race, the daily feeds can contain up to 10% more grain than normally provided, with the bulk made up of good quality, dampened hay and chaff to replenish energy stores, restore intestinal motility and fluid retention in the hindgut. If a horse is given a rest or a light workday, ideally as turn-out for self exercise at pasture, the grain content of the meals should be reduced by 50% until the horse returns to training.

2. A muscle buffering citrate based alkaline electrolyte preparation, over the tongue, or in the feed, for 2 mornings after racing will assist in lactic acid elimination after intense exercise.

3. There is evidence from research in other athletic animals that an additional 2% protein added to the diet, particularly high lysine sources, such as 2 cups of soyabean meal or, alternatively, 3 cups of canola meal, can aid muscle recovery and help maintain muscle mass when provided for the first 2 meals after each trial or race.

4. An elite Standardbred inhales up to 2250 litres of air per minute into its lungs, often carrying dust, mould and airborne allergens deep into the lungs, especially if trained or raced on a dusty track. Normal respiratory tract clearing mechanisms may be overloaded, particularly if a horse is transported a long distance after racing. Accumulation of fluid and debris, including blood cells from lung bleeding, must be cleared efficiently during the post race period. If possible, a horse should be turned out to graze for a few hours on each of the 2 days after the race, with its head down to facilitate airway drainage. Alternatively, providing dampened feed in a feed bin below chest height for at least 2 days after racing will assist airway clearance.

Horses in training may develop a number of dietary related problems, most commonly resulting from feeding high grain diets as the major energy source.

Some horses do not do as well and perform at a lower standard than expected when in race training. Often a blood count is taken to evaluate a horse’s adaptation to training or to confirm an underlying metabolic problem. A low blood count in a racing horse is most commonly due to blood loss resulting from developing Small Redworm burdens, or insufficient all-out fast work in training to stimulate blood cell synthesis.

It is best to worm a horse at the start of training, repeat in 3 weeks, and then at regular 6 weekly intervals.

Although most textbooks and equine physiology specialists state that horses in training receive an adequate dietary intake of iron without the need for supplementation, many trainers consider that extra iron is beneficial to their horses. The survey by Dr. Louise Southwood and colleagues reported that Standardbreds in training received 125-381% of iron above recommended amounts each day. Some leading trainers supplement their horses with up to 600mg iron in the feed each day. Heavily sweating horses, such as Standardbreds in heavy training, can lose appreciable amounts of iron (23mg iron/L sweat) in the 15 - 20 litres of sweat lost each day.

Cereal grain based rations may be relatively deficient in available iron. A supplement of iron is commonly added to the feed each day for the first 4-6 weeks of training. This provides adequate iron for blood cell production in response to increasing oxygen uptake as exercise duration and speed is increased. There is generally no need to administer iron injections, as there is an associated risk of acute shock reaction.

To help improve the oxygen uptake, a horse can be given short bursts at all-out speed over 300 - 400 metres twice weekly at the end of a fast work morning to maximise the red cell response and oxygen carrying capacity.

As a horse becomes fit in training, its appetite often decreases and it may consume 5-10% less bulk of ration. Many smaller framed, nervy horses go off their feed when pushed hard at the start of regular fast work and when raced repeatedly. Dr. Louise Southwood and colleagues in their 1993 survey linked loss of appetite to intensive training programs, climatic stress and feeding larger volumes of grain in 2 or 3 feeds with minimum roughage as hay instead of spreading the total grain fed over 4 feeds. The loss of appetite could be the result of low-grade hindgut acidosis that develops in the hindgut when more 2.5kg of raw grain is given in any one feed. Studies indicate that up to 50% of horses that become picky eaters in training have low-grade gastric irritation and ulceration due to high grain diets. Others suffer from poor teeth, or are fed excessively bulky rations that they are unable to consume to meet their needs.

Horses that are fed on a high grain diet with a minimum amount of chaff or hay are likely to develop a chronic form of dehydration, especially during hot or humid weather conditions. Humid conditions do not increase the amount of sweat loss, but significantly reduce the efficiency of evaporation and cooling effect during exercise and during the cool down period. Signs include a prolonged pinch-up in the skin, ‘tucked-up’ in the belly, and a dull rough coat. Horses that pass low grade ‘cow pat’ droppings on high grain diets (hindgut acidosis), or nervy horses that become ‘loose in the bowels’ when travelling or on raceday are also likely to suffer a low grade chronic dehydration due to excess fluid loss in their droppings.

Electrolytes added to the diet each day will increase a horse’s desire to drink more water, thus replacing lost salts and restoring fluid balance. It is essential that water be provided at all times when electrolytes are being given in the feed or over the tongue. If a horse is dehydrated 72 hours prior to a race, electrolytes in water as a saline drench may be given. Alternatively, a rehydration fluid can be given over the tongue each morning and night ensuring free access to water until the race. (Refer to the above recommendations for saline drenches).

A horse with a nervous or highly reactive temperament can expend up to 60% of its total race reserve of energy moving about in the stable and yard over a 24 hour period. Many young and immature horses develop ‘track nerves’ when in training, and on raceday ‘run their race’ during travelling or before the start.

Reducing the risk of hindgut acidosis by replacing raw grains with extruded (cooked) grains, or replacing some of the oats or grain with oil as a ‘cool’ energy source may reduce ‘hyper’ behaviour.

Specific supplements containing Vitamin B1, Vitamin B2, magnesium and tryptophan can be provided to assist in calming and settling a nervous horse, but they are usually best given for 5-7 days prior to racing.

A nervous, picky eater may do better on 10-15% less grain, combined with more roughage, and if given access to a day yard or small paddock and the opportunity to relax when grazing. In some cases, full training from the paddock may be necessary to prevent a nervy horse fretting and losing weight when in training.

Tying-Up

Young horses in training, particularly mares and fillies when in season, nervy horses, and those that sweat heavily are likely to tie-up during, or within 2 hours after exercise. Tying-up is most common in horses that are worked after a rest day on high grain diets.

Some horses, particularly lightly built young fillies during the early stages of fast work, develop symptoms of a shortened stride and hindlimb muscle soreness within 6-24 hours after a hard workout. This may be due to lactic acid accumulation from anaerobic metabolism in the unfit muscles before oxygen uptake capacity is maximised. Many of these horses lose their appetite and develop a ‘sour’ temperament for 2-3 days after a hard fast workout. A supplement of a citrate based alkaline buffering electrolyte for two mornings after a hard fast exercise workout can be used to avoid these symptoms.

Guidelines to prevent tying-up, or recurrence of tying-up, include:

 þ   Cut back grain feeds to one-third on rest or light work days, starting the evening before, taking two days to restore the full amount once work resumes. Feeding extruded grains and oils as the primary energy source can significantly reduce the risk.

þ    Provide electrolytes and water to maintain fluid levels in working, heavily sweating horses. Provide a Vitamin E/Selenium supplement daily.

þ    Warm the horse up for 5-10 minutes before fast work. Cool out at walk for 1 minute initially then trot-out after work for 3 - 5 mins.

þ    Ensure the horse is fit for the speed and type of exercise or competition.

þ     Give mares in season extra electrolytes in feed to replace potassium and magnesium.

þ    Use of a muscle buffer containing citrate salts after work may help reduce the risk in some horses.

þ    Where young nervy fillies continue to ‘tie-up’ – supplement the diet with a ‘nerve’ supplement.

Oats is taken as the standard grain for energy, and the relative energy content and substitution weights of other grains and feeds are listed in comparison to this standard. For example, 1kg or 2 Litres of oats can be substituted by 830g or 1.3 litres of crushed lupins or alternatively 900g or 1.4 litres of rolled barley to give the same energy level. All other grains can be substituted in a similar way, eg. each 850g or 1.3 litres of crushed lupins in a ration can be replaced by 610g or 1.3 litres of black sunflower seeds for equal energy.

*Cupful = 250mL standard metric cup.

In practical feeding terms, this means that:-

In practical feeding terms, this means that:-

When the amount of oil given each day exceeds 2 cupsful (500mL) as a substitute for grain, for each additional cupful of oil mixed into the ration add all of the following supplements daily.

Soyabean meal is taken as a standard protein source, and the relative substitution weights to provide the same amount of protein can be made up from single or multiple sources of protein meals. For example, one cup of soyabean meal can be replaced by 1.5 cups of canola or cottonseed meal for the same amount of protein. Because of the variation in weight and protein content, 2 cups of crushed tick beans are required to replace 1 cup of soyabean meal for equal protein.

Kohnke JR 
Feeding and Nutrition of Horses – The Making of a Champion Vetsearch International Sydney 1998 p. 93-105

Kohnke JR, Kelleher F and Trevor-Jones P
Feeding Horses in Australia A Guide for Horse Owners and Managers Published by RIRDC Canberra, Australia 1999 pp. 69-75, 127-128

National Research Council 
Nutrient Requirements of Horses Revised 5^th Edition, National Academy Press, Washington DC, USA, 1989 pp.

Southwood, LL, Evans, DL, Bryden, WL, Rose, RJ (1993) 
Nutrient intake of horses in thoroughbred and standardbred stables Aust. Vet. Journal 70 p. 164-168

Southwood, LL, Evans, DL, Bryden, WL, Rose, RJ (1993) 
Feeding practices in thoroughbred and standardbred racehorse stables Aust. Vet. Journal 70 p. 184-185