Feeding Thoroughbred Racehorses

Thoroughbred racehorses require an adequate and balanced diet, providing the energy and full range of essential nutrients to meet the high demands imposed by training and racing. In young and growing 2-3 year old horses, additional energy, protein, calcium and trace minerals must be provided for performance and growth, as well as enable bone modelling and development of muscle.

The ration must provide all the essential requirements, whilst catering for a horse’s individual needs according to its weight and stage of training, age, exercise demand and temperament. Adjustments to the feed mix, type of additives, and reduction in bulk of feed may need to be made during a horse’s preparation to maintain vitality and ensure the horse can consume the volume of feed as its appetite decreases under the stress of regular fast exercise.

A well formulated hand-mixed ration provides the flexibility required to match an individual horse’s changing demands, likes and dislikes and appetite level throughout its full training and racing campaign.

Basic nutritional requirements for thoroughbreds

Energy

Once a horse comes into training, the energy requirement to fuel muscle activity and body functions increases in proportion to the intensity and duration of exercise. By the time the horse is fit and ready to race, its energy intake is double that required to maintain it when at rest and grazing, although the horse may not be able to eat a larger volume of feed. In young, growing 2 year olds, adequate energy must be provided for growth, development and performance. An inadequate intake of energy will reduce growth and response to training and will result in weight loss and less than optimal performance.

Sources of energy

The traditional sources of energy are provided by whole oats, with varying amounts of cracked corn or rolled barley, whole sunflower seeds, and occasionally cracked lupins and beans, depending on availability. Whole oats are normally well tolerated by most racehorses and are normally provided at feeding rates of up to about 5 kg daily. Rolled barley is more of a “conditioning” and “cooler” energy source and is often used in horses requiring extra body weight, those prone to tying up or young horses. Cracked corn is a very energy dense grain and as it is not as well digested compared to the other grains, is normally limited to about 1.5 kg daily.

Fats & oils as an energy source

Vegetable oil is often used in racing rations as an extra energy source. There are several benefits to feeding oils/fats in the diet. During extended exercise, aerobic metabolism of fatty acids can delay blood glucose and glycogen depletion, resulting in higher muscle reserves being retained at the end of exercise and lower lactic acid accumulation. Studies also suggest that fat substituted for cereal grains can reduce gut fill and hindgut weight, which may increase speed and reduce fatigue in horses working over distances greater than 1600 m. Each oil or fat has a blend of different fatty acids (Omega-3, Omega-6) in its triglyceride content and a correct ratio of these is essential. Canola oil is generally suitable in its pure form. Oil should be added fresh each day to the meal at feed time to prevent oxidation and Vitamin E should be supplemented to ensure best utilisation. If adding vegetable oil to feed, it’s also important to gradually build up to a cup to avoid any gastric discomfort.

Protein

Proteins are composed of amino acids: essential amino acids (these must be provided in the diet) and non-essential amino acids (these can be produced in the body and do not need to be added). Protein sources composed of a high proportion of essential amino acids are referred to as high-quality proteins. These include extruded full fat soyabean meal, cracked/crushed tick beans and crushed/rolled lupins.

Studies indicate that the amount of protein needed increases with increasing physical activity. The estimated protein requirement, relative to energy intake for light, moderate and intense work is shown in Figure 1.

Fig 1. Crude protein requirement of a 500kg horse at varying levels of exercise (NRC, 2007).

This increased protein requirement is needed for increased muscle development and mass with increased physical condition; an increased muscle protein content and also to replenish nitrogen lost in sweat.

When racing repeatedly, adequate protein must be available to help repair and maintain muscle mass, especially in the 24 hours following intense exercise. There is however no benefit in supplying too much protein in the diet. Excess protein leads to excretion of urea in the urine which increases urine volume and water requirements and can lead to higher heat waste from fermentation, elevated heart and respiratory rates and may have an adverse effect on athletic performance. It also increases the ammonia smell in the urine which can be noticed in poorly ventilated stables when horses are fed higher-protein-containing feeds.

Fibre (roughage)

Adequate fibre as hay or chaff must be supplied to balance the high energy diet, ensure efficient hindgut digestive activity and function and help maintain an adequate reservoir of water to combat dehydration.

As a guideline, a balance of 60-70% by weight of grain mix to 30-40% by weight of chaff and hay is adequate to maintain digestive function. In nervy horses or those in hard work, access to pasture provides extra roughage, relief from stable routine and improves appetite and overall digestive function.

Optimum vitamin, mineral and trace mineral intakes for thoroughbreds

Minerals and vitamins

An adequate intake of essential minerals and vitamins must be provided on a daily basis, and the rate of supplementation varied during the training period to meet increased requirements relative to the age of the horse, the stage of training, sweat loss and physical stress during training.

Major minerals

Calcium and phosphorus

A daily supplement of calcium is required to meet the increased demands of skeletal growth and remodelling that is stimulated by fast exercise. The front cannon bones of young horses in particular, must thicken and strengthen to adapt to increased loading forces imposed by all-out galloping around corners on a race track. Equally important is an adequate supply of phosphorus as phosphorus deficiency can result in retarded bone formation and poor appetite. The diet must not only contain adequate amounts of calcium and phosphorus, these nutrients should be supplied in an appropriate ratio so the animal can absorb and utilize these nutrients (a sufficient excess of either mineral will decrease the absorption of the other). Grains are typically high in phosphorus and low in calcium. Lucerne hay on the other hand is higher in calcium than phosphorus. Selection of an appropriate supplement such as Virbac’s CAL-PLUS^® with BIOTIN provides these key nutrients to meet the elevated demands for bone modelling in response to exercise and allows for an optimal ratio of these minerals in the final handfed ration.

Trace minerals and vitamins

A “foundation” supplement such as FERAMO^® EVERY HORSE or FERAMO^® with CHROMIUM will provide a broad range of essential vitamins and trace minerals to correct low or inadequate levels in the ration relative to exercise demands. FERAMO^® provides a basic level of iron, copper and vitamins for blood production, vitamin A to help maintain tendon strength, and B-complex vitamins, zinc, iodine and selenium for energy utilisation and muscle strength.

Other specific supplement needs

Other specific supplements of iron, vitamin E, calcium and electrolytes can be added to meet specific needs during training. This can avoid the expense of over-supplementing and imbalancing the complete range of minerals and vitamins to horses, as often occurs when complete, prepared feeds are used as the major energy and protein source in the ration.

Optimum electrolytes intake for thoroughbreds

Electrolytes

A routine daily supplement of a high potassium electrolyte replacer, such HUMIDIMIX^® is recommended to replace sweat loss and maintain water intake. When travelling, 60-80 mL RECHARGE^® over the tongue with cool water provided to drink before and after travelling will help to rapidly restore electrolyte and fluid levels, vitality and assist recovery.

Horses with symptoms of dehydration (tucked up in the belly, dry pinched-up skin) in the 2-3 days prior to racing can be given 60 mL RECHARGE over the tongue each morning and evening, with access to water, and in most cases, a saline drench will not be required.

What to feed thoroughbred horses

The table below outlines a suggested feeding program for a 500 kg thoroughbred in early training and full work (racing), and based around Virbac supplements.

Please note the above feeding program is intended as a guide only. Please alter feeding rates according to individual horse bodyweight and workload. It is recommended that any new feed ingredient be added to the diet in a gradual and step-wise fashion to reduce the risk of digestive upset.

¹ The amount of barley may be increased, and oats reduced for excitable horses and for horses prone to tying up. Please note that barley is more energy dense and weighs heavier than oats. As a guideline, every 1 kg (volume 2 litres) of oats removed may be replaced by 900 g (volume 1.4 litres) of rolled barley.

Please be advised that the suggested rations are intended as a guide only. The most reliable method of obtaining nutritional information about ingredients in the diet is by analysis of samples of individual batches of feeds. The values used in these analyses are based on Australian and overseas literature. There may be some variation in the nutrient composition of feeds depending on the quality of the feedstuffs and the feed source. The information provided in this document is based on the National Research Council Nutrient Requirements of Horses (2007) publication. The actual amount of feed offered may need to be altered depending on the horse’s individual metabolism, and the quality of available roughage. If the horse in question has any health concerns, consultation with your veterinarian is advised prior to changes in feeding programs.