Endurance Riding, Part 3, Section 2

Exercise, Feeding and Energy Sources

By Kristene Smuts

Feeding the Endurance Horse

Please remember that as your conditioning programme becomes more intensive, you need to keep an eye on the condition of your horse. You can't keep feeding the same amount of food as you did when he was a pasture ornament, as he'll soon start losing body condition. When he's at rest, you shouldn't be able to see the ribs, but should be able to feel the last two ribs when you run your hand over his rib cage. The hip bones should not jut out either and the hollow just in front of the hip bone should be filled in.

Golden rule number 2 : Never make changes or add anything foreign to the diet just before or at a ride. You'll see a DECLINE in performance, NOT AN INCREASE!

There are 3 points to remember as you increase your training : first prize is hydration, a close second is gut motility and a distant third is energy. If you pay attention and manage the first two well, the third will merely be a bonus for good performance. The absence of the first two is what gets you disqualified at a ride where the absence of the third won't. We'll be discussing the nutritional and feeding requirements under these 3 headings.

To understand the way foods and supplements are digested and converted, we'll first discuss how the horse's gut and blood flow works. Much more detailed descriptions are available, but the following simple explanation should suffice.

The food is ingested and is moved down the gullet by peristalsis (flashbacks to your high school biology class?) to the stomach through a muscular, one-way valve (that's why the horse can't vomit). It reaches the small intestine where enzymes, produced by the liver and pancreas, are used for the initial breakdown of the food. Protein, fat and carbohydrates are broken down to form glucose. The bloodstream picks up the glucose for transport to the muscles and liver, where it's stored as glycogen. The remainder of the food is passed to the large intestine where fibre (hay and grass) is broken down by microbes or bacteria.

Fibre absorbs and holds water and electrolytes for use in the large intestine. Water is moved through the gut wall to the blood, where it forms the plasma - that's what makes the blood thin and runny. The large intestine is fairly long and is folded on itself with a narrowing in the pelvis area - this is where blockages occur which cause colic. The unprocessed food is moved to the small colon where water and electrolyte absorption continues after which the unutilised food is excreted via the rectum and anus. If you analyse your horse's droppings, you'll be able to see what parts of his food hasn't been digested - very often you'll see bits and pieces of maize still present. The entire digestive process may take as long as 2 days.

The metabolic process in the small intestine generates short, intense heat, where the heat generated in the large intestine is not as intense but lasts much longer. That is why feeding hay on a cold day will keep your horse warmer than feeding one large protein rich meal.


One of the primary jobs of water in the horse, is to rid the body of internal heat through sweat. During an average 80km endurance race, a horse can generate enough internal heat to melt a 70kg block of ice and bring the water to a boil. A dehydrated horse stops sweat production, causing his internal heat to escalate. Blood loses its fluidity, causing the blood to become like sludge, which in turn causes the heart to work harder to circulate this sludge. When the horse is dehydrating, the circulatory system will attend to the vital organs first - the heart, liver, lungs, brain - and leave the intestines without blood supply. This causes gut motility to slow or stop entirely, only resuming once blood flow is restored.

Hydration isn't just how well your horse drinks, but the actual availability of fluid in the body. As the horse exercises, he can lose between 7 and 18 litres of fluid per hour through sweat, about 4% of total body weight in the average horse. Over a distance of 80kms, this can add up to more than 45 litres of fluid lost, 10% of total body weight. These numbers represent the unreplenished quantity of fluid in the body, meaning that a horse who has been drinking during the day may still become dehydrated. A mere 8% fluid loss will result in a 2-3 second capillary refill time, dry faeces, a high pulse and dry mucous membranes and gums. A 10% fluid loss requires immediate veterinary attention and a horse who has lost 12% fluid is close to death.

Now that I've scared you witless - intentionally, mind you - we can now discuss how to avoid having a horse that may need an IV at the vet check. As little as 23 litres of water (a largish bucket) can make the difference between a dehydrated horse and one that is fit to continue. External things would include keeping his hair short, especially immediately after winter when you haven't had a chance to groom all those long hairs out - but keep in mind that you'll have to blanket during the night to keep the chill away; sponging him down at every water stop; your tack should cover a minimal part of the body; your saddle pad or blanket should be thin but sweat absorbing; and most importantly, he should be fit and sleek and up to the challenge.

Now for the internal things you can do to aid in hydration. Remember that water absorption occurs in the large intestine and fibre, in the form of forage, is digested here. Forage stimulates drinking and by feeding more forage at least a week before a ride, will aid in water retention. Although a large quantity of water would have been absorbed, you'll still have a decent reservoir of fluid to draw upon. Make sure you have an ample supply of hay available during the trailer trip as well as when you get to base camp. Give one dose of electrolytes the night before the ride to encourage drinking.

The timing of meals is also very important. When you feed more than about 2 kilograms of food at a single sitting, blood plasma shifts to the digestive tract, thereby thickening the blood. In the average horse, this can be as much as 20 litres of fluid. Whilst this would not affect a horse standing around doing nothing, asking your endurance horse to do strenuous exercise in this period of blood fluid starvation would have disastrous effects on his performance. This fluid shift will correct itself within a few hours, so avoid feeding large meals within about 3 hours of asking for any kind of exertion. Teach your horse to nibble along the way - not difficult to teach! - so that he will have a continuous supply of food in his digestive tract. Also, give a small meal - about 1.5 cups of concentrate - together with electrolytes mixed to a soupy consistency with chopped-up carrots when you come back to base camp - but remember only when the horse has cooled down sufficiently!

Gut Motility

The digestive tract stands in line - right at the back of the queue - when blood is supplied to the different organs. When a horse goes into a high level of stress, whether it's moving home or doing unaccustomed exercise (anaerobic exercise), the digestive tract is the last "organ" to be supplied with blood. When the horse becomes stressed, blood is diverted towards the vital organs - heart, brain, muscles - leaving the digestive tract depleted of blood fluid. This will cause the gut to slow dramatically and even come to a standstill. Should the gut be in this state for too long, gasses from fermenting food will accumulate, causing colic. This is the reason why you should learn to know your horse's gut sounds, so that you can tell when he's going into a state of emergency, colic wise. Slow or absent gut sounds are always an indication of dehydration which is the result of pushing your horse too hard.

Remember that when the horse is dehydrated, the blood becomes thicker and the heart has to work harder at circulating it, causing a higher heart rate, and electrolytes and water cannot be delivered to the gut. With the gut slowing down or coming to a standstill, it inhibits the gut to absorb and use much needed water and electrolytes, which is needed for improved blood flow - you've now created a vicious cycle.

When do you know your horse is in trouble? Spending hours and hours with your horse, will soon tell you that he isn't as perky as he should be; he's not moving out as easily as normal; he's not drinking and has lost interest in eating. Don't panic. Listen for gut sounds and make an educated guess as to the severity of the situation. If you're out on the trail, simply slow down to a calm walk, preferably not riding him, thereby giving the body a chance to recover by allowing blood flow to be re-established to the gut. Allowing him to graze and drink along the way will also aid in correcting the situation, helping with hydration as well. Don't stop entirely, keep moving so that the muscles can rid itself of accumulated lactic acid in the muscles.

Should you find yourself in trouble with your horse due to over-extension, do the clever thing and withdraw from the ride. If you managed to correct either hydration or gut motility problems before it's picked up by the vet, remember that your horse got into trouble once during the day which puts him at greater risk of getting into bigger trouble later on. Remember that the distance you're away from camp is still the same distance you'll have to travel back should your horse be in trouble - this may sound logical, but soon forgotten when you're caught up in the excitement of the ride.

Knowing your horse as well as you do, you'll be able to tell if he's on the brink of trouble even before the vet can pick it up. Don't wait, rather withdraw to ride a healthy and happy horse again some other day.

If you should decide to continue the ride and something happens to your horse, the chief vet and ride master will determine the severity of the situation, you'll be charged with negligence and, depending on the outcome, banned from the sport for life! So please don't risk your horse's life and your name by making the wrong decisions.

But having just said that, you should see the vets as your friends. If you're not sure about something, they'll be more than willing to assist and advise you, taking time to explain the finer points of pulse, hydration, gait and gut motility. They'll treat your enquiry with the necessary attention as they have the education of the riders as well as the horse's health in mind.

Part 3, Section 3