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For optimum performance, horses require energy from numerous sources. A combination of fibre, starch, and fat is the best way to fuel performance, and the ratio of these sources provided in the diet will depend on the type of work that is required from the horse. Due to the especially heavy demands of racing, the ratio of energy sources for racehorses is arguably the most important to get right.

Structural carbohydrates in the form of pasture, hay, chaff and fibre products are essential components of the equine diet. Each horse requires a minimum of 1.5% of their body weight in forage daily to maintain optimum digestive health. Horses have a highly developed hindgut that houses billions of bacteria and protozoa capable of fermenting large quantities of fibre. The end products of fibre fermentation can be used as energy sources throughout the day because fermentation continues long after a meal has been eaten. 

Since proper gut function is essential to the health and well-being of the horse, fibre-rich forage should be considered the foundation of any feeding program. Pasture and grass type hays are ideal for making up the bulk of forage requirements, and the inclusion of lucerne at smaller amounts has fantastic benefits to working horses. Lucerne is higher in energy and protein than most grass type forages, and the higher calcium it contains increases buffering qualities against gastric ulcers. Lucerne should be a part of the diet for all harder working horses, especially racehorses that can be particularly prone to digestive conditions.

Grains supply fast release energy through non-structural carbohydrates, particularly starch. Starch is therefore an essential energy source for any horses where fast paced work is required, such as racing. The starch in grains is converted to blood glucose when digested and is the first form of energy the horse uses. Remaining glucose not utilised initially, is converted to glycogen and stored in the horse’s muscle and liver for use when next required. Glucose is one of the major energy sources that provides horses with fast release energy for work, and the amount of glucose available to the horse at the start of exercise is relative to the last meal the horse consumed. 

It is important that glycogen stores are replenished after each period of exertion, to ensure stores are at adequate levels for the next heavy work period or race. Remaining glycogen levels can make a significant difference to how a horse finishes a race.  

Despite the obvious benefits of starch as an energy source, it is important that it is fed correctly to avoid digestive conditions. To reduce the risk of gastric ulcers and hindgut acidosis, grains that have been processed through heat and pressure are recommended, such as steam flaking or pelletising (with the exception of oats which are digestible enough to be fed whole) as well as keeping meal sizes to 2.5kgs and below. 

Similar to fibre, fat is a slow release energy source that has numerous benefits to working horses. It is a highly dense form of energy, containing 2.5x the energy as the same amount of oats. This makes it great for weight gain and fussy horses that can't eat large volumes.

Fat also has an important role to play in racehorse diets as it can assist with exercise efficiency and recovery. 
While every discipline requires a combination of each of the three energy sources, adopting the correct ratio depends on the individual horse and the work asked of them. Race work relies heavily on non-structural carbohydrates such as starch as the initial energy source, however structural carbohydrates such as fibre is essential for digestive health and fat is important for stamina and recovery. 

With starch from digestible oats and steam flaked grains, fibre from beet shreds and fat from cold pressed canola oil and cold pressed flaxseed flake, McMillan Energy Max provides hard working horses with the optimum blend of energy sources to fuel their performance.

For more information on racehorse nutrition contact a qualified equine nutritionist.

Luisa Wood
Equine Nutritionist

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