SO YOU THINK YOU KNOW PROTEIN

SO YOU THINK YOU KNOW PROTEIN This month we’ll look at protein in the horse’s diet. This article isn’t meant to tell you how much protein your horse should have- that is a conversation to have with your veterinarian, and your horse’s requirements will depend on his age, job, and activity level. Each horse is an individual and should be fed as such. We’ll talk here about what protein does, types of protein, and how to determine how much your horse is getting in his diet. Before we go further, let’s get a couple of misconceptions out of the way. First, protein does not make your horse hot. Excess energy, generally in the form of carbs, is what leads to those exuberant moments. Remember too that some horses just are hot: that is their nature. Eating enough protein helps them to be fit and feel good but in and of itself it is not a cause of hot behavior. A second misunderstanding is that exercise builds muscle and that’s not true either. Protein builds muscle. Exercise conditions it. More on this later. Protein is so important that we could go on for pages and pages…but we won’t. You should know though how necessary it is to the equine body. The horse needs to eat protein daily because it affects so many body functions. Here’s the short version: it provides structure in the forms of bone, muscle, cartilage, skin, and hooves. It is responsible for growth and maintenance. It drives biochemical reactions such as digestion and blood clotting. It maintains the pH of body fluids and helps balance the fluids in the body (think swelling and inflammation.) It bolsters the immune system and helps to store and transport nutrients across membranes and in the blood. Protein provides energy and even affects saddle fit. Let’s address the protein and energy question here. I wrote earlier that protein does not make your horse hot, and now I’m telling you that it provides energy. Protein can be a source of energy, but it is metabolically expensive. It is such a valuable component that the body prefers to use it for other functions. Energy also comes from carbohydrates and fats, both of which break down easily. Carbs and fats are easy to store, and well-fed horses have an abundant supply just waiting to be tapped. If your horse couldn’t eat, he would eventually run out of his stored fat and carbs and his body would then start to use protein as an energy source. It’s hard work for the body to break down protein for that use however, and it has the added burden of generating excess nitrogen which must be excreted. Here is another view: gram for gram, protein and carbs have the same number of calories (with fat having twice as much) but it’s easier to extract that energy from the carbs than from the protein. It is much more efficient to use protein for the other systems in the horse’s body. Think of it this way: yes, you can use your jack knife to open a can, but isn’t it easier to use a can opener? The jack knife has other uses for which it is better suited. Same with protein. Yes, it can be an energy source for your horse, but it’s easier for his body to use carbs and fats. Protein’s real role is for other functions in the body. As stated earlier, exercise does not build muscle. Protein builds muscle. You can do all the exercises you wish but if there isn’t sufficient protein in the diet, muscling won’t happen. When a horse isn’t getting enough quality protein, you may notice that his topline drops and your saddle fit changes. That’s right- your saddle fit problem may be one of diet, not exercise. This is even more noticeable as horses age. We know that older horses don’t utilize nutrients as efficiently and as effectively as do younger horses, and this is why senior feeds tend to be higher in protein. The horse’s body contains thousands of different proteins. Every cell in his body contains some type of protein. Does it surprise you to learn that? Protein is not just “one size fits all.” The protein that produces a hard hoof is not the same as that which transports nutrients in the blood, and both of those are different than the one that builds muscle. In order for all this to happen, proteins are constantly being broken down and synthesized by the horse’s body. This is why quality protein is such an important part of your horse’s diet. Hopefully by this point you are realizing that protein isn’t really an ingredient- it is a legion of multi-faceted, multi-use units. Amino acids are the building blocks of those units. We won’t go into detail, but there are a few important points you should know. First, amino acids are categorized as either nonessential or essential. Now that does not mean that the horse needs some but not others…not even close! Nonessential means that the horse can synthesize the amino acids in his body. Essential means that he cannot synthesize them or cannot synthesize enough to fuel his needs. There are ten essential amino acids (EAAs). Of these, most people have heard of lysine, methionine, and threonine, because they are limiting essential amino acids. This means that if there aren’t enough of these, the other proteins can’t be synthesized. An example: if you are building an electric fence for your pasture and you run out of insulators, it doesn’t matter how much wire or how many posts you have. Without more insulators, your project won’t get done. Those insulators are like limiting essential amino acids. Current research indicates that lysine is the most restrictive limiting EAA. If you are feeding a quality feed, it hopefully has lysine and maybe methionine and threonine listed on the guaranteed analysis. If you don’t see these listed on the bag tag, this doesn’t mean that your