CARBOHYDRATES AND CONFUSION: Sugars and Starches and Energy

CARBOHYDRATES AND CONFUSION: Sugars and Starches and Energy This month’s article is the final part- for now- on carbohydrates. We’ll certainly talk about them again in the future, because carbs are such an important part of the horse’s diet. Today we are going to focus on what sugars and starches do and why they are so important to our horses, and how to determine how much your horse is eating…sort of. It’s hard to get an exact number but we’ll talk about the parts that you can figure on your own. What this article will NOT do is tell you how many units of sugars and starches you should be feeding your horse. That is a discussion to have with your veterinarian. Each horse is an individual and should be fed as such. Your horse’s carb requirement will depend on his age, activity level, overall health, access to forage, breed, environment…so many factors! When you talk with your vet about your horse’s diet, make sure that you understand WHY the vet is making these recommendations. Your vet may mention a feed product by name. Ask him or her why they recommend that product specifically. There is a reason for this: that particular feed may not be readily available in your area, but if you know the specifics, your knowledgeable feed store can help you make a close match. As we’ve discussed before, veterinarians have a lot of information to remember. When you consider the medications and dosages, diseases, anatomies (and so much more) that they must remember, it’s a bit unrealistic to expect them to keep up with the latest feed products too. A couple points to clarify: usually when people refer to carbs, what they are really concerned about are the sugars and starches. But you will remember from last month’s article that fiber is a carb too and should be the largest part of your horse’s diet. For ease of use, I’m not going to refer to sugars and starches as carbs in this article. I’m going to call them sugars and starches. If I use the word “carb” or “carbohydrates”, then I’m referring to sugars, starches, and fiber. A quick overview from the last two months: carbohydrates are sugars, starches, and fiber. There are several different ways to categorize carbs depending on their chemical formula, digestibility, and source. Some complex sugars and starches break down into simple sugars in the horse’s small intestine. Other complex sugars, such as fiber, do not break down easily and instead are fermented in the horse’s hindgut. The fermentation provides energy for metabolic processes, including keeping the horse warm. Fiber contains a large amount of indigestible matter, such as lignan, so in addition to producing heat, it also produces a lot of waste. Then you scoop it up and wheel it out to the manure pile. The sugars and starches that break down in the small intestine are reduced to glucose, which is absorbed into the bloodstream. This triggers a release of insulin which helps move the glucose from the bloodstream to the body tissues. Then the glucose can be metabolized to release energy or stored for future use. Horses need energy to move their large muscles and for everyday functions such as breathing, maintaining (or gaining) weight, and for powering their brains. It turns out that the horse’s brain is an energy hog. According to the book “Horse Brain, Human Brain” by Janet L. Jones, PhD, the horse’s brain is 0.67 percent of his body weight (about the size of your fist) but uses 25% of his body’s glucose supply. That’s a huge portion. Obviously, a non-sugar and starch diet isn’t going to work. The horse needs these nutrients. So why are we so concerned about how much the horse eats? It’s because of the impact of too many sugars and starches on his health. And this is a good place to switch to the use of the terms “calories.” When we talk about calories with a small c, we using it as a general term of energy. When we speak of Calories with a large C or kcal, that is a specific measurement and it means the amount of energy needed to raise the temperature of one gram of water by one degree Celsius. It’s like using the terms “shoes” versus “Nike.” One term is general, the other is more specific and tells you exactly what you are dealing with in a quantitative way. Active horses, such as those who are competing, giving lessons, or doing some sort of work every day, need to have the energy (calories) supplied by sugars and starches. Inactive horses need less. If they eat too many calories, they gain weight and can develop metabolic issues. Horses, like humans, are very good at storing extra calories as fat. This carries him through when food is in short supply, the weather turns cold, or his lifestyle becomes more active but extra food isn’t available. He can burn that stored fat and it releases energy to fuel his body. We’ve all heard stories of owners who are surprised to find that their horses are “ribby” after they shed their winter coat. The most common scenario is that the horse wasn’t getting enough calories to keep him warm, and had to resort to burning his fat stores. (This is another good reason to increase your horse’s hay in winter, as long as he can eat hay. Not only does it provide more calories, it also provides more metabolic heat because the fiber is fermented, not digested. See last month’s article.) Now I know that many of you have heard, and maybe still believe, that corn will help keep your horse warm in the winter. I’m going to stop you right now before you buy another bag at your feed store. No, corn will not keep your horse warm during cold weather. Hay or forage will do that job. Here is what adding a large amount of corn