Question
What is the best way to feed a little extra before a competition in which my horse is going to do more than normal work? For this past weekend’s competition, I gave him an extra pound (one-half kilogram) of grain two days before. Is this enough to make a difference? Or should I start earlier? Or not bother? I just like to know there is enough gas in the tank, if nothing else for safety at the end of a cross-country course.
Answer
Making sure your horse’s tank is filled with fuel for the competition might not be as easy as you think. To understand how to feed before an event, it is important to think about what the horse will need for the competition. Horses will draw on different fuel sources during a competition. The major ones are blood glucose, muscle glycogen (and to a lesser extent liver glycogen), and muscle and stored triglycerides (fat). How to manipulate these stores can be tricky because it will affect how much energy the horse will have for performance.
The amount of glucose available to the horse at the start of exercise will be relative to the last meal the horse consumed and the effect of adrenaline on mobilizing glucose when the horse is keyed up in anticipation. The timing of the feed can have an effect on the availability of blood glucose. If a grain meal is given within three hours of performance, insulin will be high after the rise in blood glucose from the meal and will be putting glucose into storage instead of having it ready for exercise. The result may be a glycemic crash and loss of energy shortly after starting exercise, because the glucose is both being used and tucked away, so there is a precipitous drop below pre-exercise levels. To avoid this problem, do not offer any concentrate meals within three hours of the start of competition. Forage does not cause the same type of glycemic response and therefore time of feeding is not as critical.
The only drawback to a gut full of forage is the extra weight that the horse will have to carry. Tapering intake of forage may be of interest if speed is an important issue for the competition. Be aware that with decreasing forage comes an increased risk of ulcer development.
Muscle and liver glycogen will be the fuel you are influencing with feeding the week before a competition. In human athletes, the practice of glycogen-loading was found to be an effective tool at increasing glycogen stores. This was done by depleting glycogen days before a competition with a really hard workout, and then feeding high-carbohydrate meals for the following days to replenish the lost glycogen. With humans, it was found that during the replenishment the levels would end up even higher than before the start of the process. When the same types of glycogen-loading studies were done in horses, the process was not found to be effective because their muscle glycogen levels are already much higher than humans. Researchers had a problem with horses tying-up in the early studies when they were given higher levels of carbohydrates than the horses were accustomed to. So glycogen-loading is not effective in horses and caution should be used in increasing the feed too much without an increase in the amount of work. Glycogen synthesis does respond to starch in the diet, so having some grain in the diet of a sport horse on a regular basis is advantageous unless the horse has certain genetic muscle disorders such as polysaccharide storage myopathy (PSSM).
The other fuel the horse will be using during the competition is fat. As long as the horse goes into the competition with good weight, the fat stores should be adequate to fuel the efforts demanded. If the horse is too thin, he will be very dependent on glycogen stores to fuel his work and may not have any staying power. In a study done at a 160-kilometer (100-mile) endurance ride, researchers found that horses with low body condition were unlikely to finish the race. They did not have enough fat reserves to fuel their work effort once the glycogen stores were tapped out. On the other end of the spectrum, it is not good to have too much body condition. The extra layers of fat may adversely affect the horse. Acting as a layer of insulation, the fat will inhibit the ability of the horse to cool. The fat also adds extra weight to carry around the course and over the jumps.
Feed management at the competition is just as important as feeding before it. If the competition is local and the drive is less than a few hours, there should be no real adjustments to the diet. However, when arriving at the competition a day or more before it starts, it may be advisable to match the intake to the needs of the horse. In other words, if the horse had a long trailer ride or becomes more active from nerves due to being away from home, he may start tapping into those built-up fuel stores before the competition even starts. Under these circumstances, increasing the feed (forage and grain) may be advisable to make sure the horse does not lose too much weight before the competition starts. The key is not to feed more at each meal than the horse is accustomed to, but to add a small meal or two to accommodate the increase. This will prevent any changes in the glycemic response to a meal, yet provide the extra calories the horse may be burning.
