Feeding endurance horses is probably one of the most debated topics around the camp fire at endurance rides. Quite understandably, newcomers to the sport often are completely confused as each of the "old timers" gives them different advice.

It gets more confusing when the topic turns to the annual Fauresmith ride. Some believe that you have to provide extra feed once the ride has started. Extra meals at midnight and again early in the morning are often said to be essential, as the horses need the extra energy.

These meals vary from the standard commercial concentrates, to buckets full of oats, religiously soaked in water. Some believe that feeding fat is the ultimate, and add a cup or more of oil to each meal. Others reduce the quantity of hay, to make room for extra concentrate or grain.

But what and when should we feed? What do performance horses really need?

Stick to his usual diet
The first and most important rule is that one should never make any major changes as to what and how you feed your horse close to competition. Horses are sensitive to major changes, and such changes could lead to gastro-intestinal disturbances, from diarrhoea to colic. Experiment with feeding strategies at home, long before an important ride, and find what is best for your horse before the season really gets going.

When a horse is fed a meal high in grain, sugar beet or another form of carbohydrate (also referred to as a meal with a high glycaemic index), the sugars are broken down in the small intestine into glucose and the glucose is absorbed into the bloodstream. Approximately two hours after feeding, the glucose levels in the bloodstream reach their peak.

The high glucose levels stimulate the release of insulin from the pancreas, which promotes the uptake of glucose from the blood into the cells of the body and at the same time suppresses the use of fat. Glucose and insulin levels gradually drop, and reach normal levels between five and six hours after the horse ingested the meal. During this period, the body is primed to rather use glucose than any other source of energy, and possibly utilises glucose more efficiently.

In another article in this edition, we take a look at the various sources of fuel a horse can use during exercise. As explained there, horses are very efficient in using fat as a source of energy, especially during the initial stages of an endurance ride. The use of fat has a sparing effect on the available glycogen and glucose, which is available for use during the later stages of the ride, thereby postponing the point where the horse gets tired.

So what happens if we follow the advice of providing the horse with an early morning meal of grain (or any other meal with a high glycaemic index), three to four hours before the start of the ride? Insulin is released and the body is primed to use glucose as its primary source of energy. Instead of using fat as a major source of energy early in the ride, the body uses the available stores of glycogen and glucose, and the horse runs out of fuel sooner.

All the hard work you put into preparing your horse by feeding fat as part of his daily ration is undone, and your horse will run out of energy a lot sooner! So rather stick to his usual diet, containing oil or another form of fat.

What about oats?
Does this mean that meals with a high glycaemic index do not have a place in endurance riding? Well, not enough research has been done to provide the answer on this, and opinions vary. As explained elsewhere, the source of energy best utilised by the body, gradually shifts from fat to glucose as the ride progresses. Therefore, during the later stages of the ride, the body is already primed to rather use glucose, and providing additional glucose probably will be beneficial.

It is not known to what extent the digestion and absorption of glucose from the intestine is affected while the horse is exercising, as the blood flow to the gut is reduced. However, if there is some digestion and if some glucose is absorbed this will make some additional energy available to the body. Therefore, providing the horse with some oats at each checkpoint, probably will be advantageous.

Feeding hay
Then there is the question of feeding hay. Hay is a low glycaemic feed and will not have an influence on the insulin levels. There also is the added advantage that horses tend to drink up to 5 litres of water for every kilogram of hay they eat. This water is retained in the gut, being held there by the fibre in the hay, and acts as a reservoir for later use during the ride.

The timing of this meal of hay is important. It does not make sense to feed a large quantity of hay an hour or so before a ride, as the large volume of feed in the gut will cause a shift of blood away from the muscles to the gut, and this will have a negative effect on muscle activity.

What to do in practice?
• Stick to your normal feeding regime before a ride. Feed the horse at more or less the same times the day before a ride, as you would do at home.
• Provide good quality hay ad lib and allow your horse to eat as much hay as he wants, until approximately four hours before the start of the ride. Thereafter remove his hay.
• Add additional grain to his feed the night before the ride. Be careful not to overload his system with grain, and do not use a type of grain he is not used to (i.e. do not feed him oats if oats are not part of his normal ration).
• Provide him with an extra meal 6-7 hours before your departure time. Stick to your normal ration (with oil or fat), and do not add extra grain.
• Give him another small meal (about
I kg of his usual concentrates) an hour before you start.
• Allow him to eat good quality hay (such as lucern or teff) at all checkpoints, with a small (not more than 0,5 kg) meal of his usual concentrates.
• Do not forget the electrolytes!