CARBOHYDRATES AND CONFUSION

CARBOHYDRATES AND CONFUSION Of all the nutrients, I think carbohydrates are the most confusing. The nutrients that we have discussed so far (water, protein, and fat) are fairly straight forward. After all, no one can deny that horses need access to water. And once you understand the roles of proteins and fats in maintaining the body, you are on your way to developing a suitable diet for your horse based on his body condition, age, and work level. But carbs…the terms alone can get you bogged down. Simple versus complex, non-structural versus structural, ADF and NDF…what does that even mean? Not to mention high-carb versus low-carb diets…so much to learn. Don’t worry, this isn’t a research paper. It’s a brief overview of what carbs are, what they do, and where they are found in your horse’s diet. I’m not going to tell you how to feed your horse, as each horse is an individual and should be fed as such. That is a conversation to have with your vet and with a knowledge feed store employee or a feed rep. You won’t be an expert when you are done reading this article, but hopefully you will have a better understanding of carbohydrates as a nutrient. Those of you with an extensive background in equine nutrition will notice that there is a lot of information that doesn’t appear here, but again, my goal is to provide a good basic understanding. We’ll break this down over the next couple of months. This month’s article will introduce you to what carbs are and what they do and will cover some of the terms that are used in evaluating and measuring carbs. Next month we’ll take a closer look at fiber, and after that we’ll talk about sugars and starches. Let’s start with a surprising fact: you won’t find a number on your feed bag for the total amount of carbohydrates. You have to do some work to determine that number, and you’ll see why as you read this article. Carbohydrates consist of three groups: sugars, starches, and fiber. Are you surprised to see that fiber is a carb? The most natural diet for a horse is fiber-based, so right away we can see that a no-carb diet isn’t going to work for horses. They need fiber, and we’ll talk more about that next month. Carbohydrates are energy. You can think of them as fuel. They provide energy for your horse’s daily existence, they give him the extra energy for the increased work that we ask of him, and when fed in abundance they can put weight on a horse. Remember though that they are not the only source of energy: fat has a hand in that game too. Carbs also power your horse’s brain. 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 but uses 25% of his body’s glucose supply. That’s right- teeny tiny brain, huge need for glucose, which is a form of sugar. (This is a wonderful book. Everyone who handles horses should read it.) Horse need carbohydrates. The big questions are what kind and how much. You may recall from previous articles that carbs and protein have similar amounts of calories, but it is metabolically more expensive for the horse to get energy from protein than from carbs. This means that another role that carbs play is to provide energy for the horse so that his body doesn’t have to break down muscle mass for energy. Carbs, like fats, are easily broken down compared to protein. Horses are adept at storing excess carbs and fats as weight, whereas excess protein is generally excreted in urine. I’m going to use some traditional terms for carbs in this article: simple sugars, complex sugars, starches, and fiber. You will see different terms used in other articles: storage sugars may be used in place of complex sugars and starches, and structural carbohydrates may be used instead of fiber. What makes up a carbohydrate? Picture a chain with multiple links of three different colors. The links are carbon, hydrogen, and oxygen, and they can be connected to form many different color patterns and units of many different lengths. That chain is a carbohydrate, and the order, number, and length of the units of colored links determine whether it is a sugar, a starch, or fiber. A simple view, I know, but we don’t really want to get into organic chemistry, do we? Here is where it starts to get complicated: complex sugars (many units hooked together) can be broken down into simple sugars. Starches can be broken down into complex sugars and then into simple sugars. Both are broken down fairly easily by enzymes and absorbed during digestion in the small intestine. These simple sugars then are used as fuel by the body. Fiber is also a string of complex sugars and starches, but it is not broken down easily by enzymes. Instead, it is fermented in the cecum and large colon to release its energy. It is the act of fermentation and the resulting release of energy that provide heat to your horse in the winter. (That’s right, feeding him more hay, not corn, will keep him warmer in the winter.) Carbohydrates are also known as saccharides. Monosaccharide is a term used for simple sugars which contain one sugar unit. These simple sugars are the smallest units of sugar. When they are further broken down, they are no longer considered a sugar. It is the breaking of the bonds holding the sugar together that releases energy. Glucose and fructose are examples of monosaccharides. Disaccharides contain two sugar units. Two examples are lactose, found in dairy products, and sucrose, more commonly known as table sugar. Oligosaccharides contain anywhere from three to 200 units, and there are also polysaccharides, which contain 200-2,000 units. As the number of units that are hooked together increases, the number of possible combinations also increases.