Protein is a clever nutrient in its ability to apply itself to the tissues as needed, but the protein level cited on a hay analysis doesn’t actually tell us a whole lot about its ability to do that. It’s the amino acid content within the protein that matters— amino acids will go into the bloodstream and the cells will then reassemble them, or try to, to make the kinds of proteins that the cells need. In the hoof cell, amino acids make hoof protein. In an eye cell, they make eye protein; in a liver cell, liver protein, and so on. To be useful to the body, though, protein must have the right combination of amino acids in the right ratios. This is what is meant by “protein quality.” If you feed one type of protein source and it’s of poor quality (doesn’t have the right complement of amino acids), there won’t be enough amino acids to reassemble and so there will be some left over, unusable. Since they cannot be saved for later, the leftovers end up going to the liver where they’re destroyed. This can result in the production of ammonia and urea, so the horse will urinate more and his urine will be stronger smelling. That’s a sign that you’re not giving enough quality protein.
But did you know that leftover amino acids can actually raise insulin levels? Inside the liver, the unused amino acids are broken apart – part become ammonia and then urea and excreted in the urine. And the other part, called an organic acid, gets converted to? You guessed , it! It is converted to glucose—which can raise insulin levels. So you can feed a low starch, low sugar diet but if the protein quality is low, you’ll still raise insulin levels. For this reason, you want to be very careful to provide a variety of protein sources so that your horse can make the body tissues that he needs. He’ll make them in order of priority. Certainly the tissues that are most important are those that keep him alive—his lungs, his brain, his heart, his liver, his kidneys. If there are usable amino acids left over, then he’ll make sure that enough antibodies are produced for healthy immune function as well as for his joints, skin, and his hair, and his hooves—but those tissues that are not life essential will suffer if the diet doesn’t contain enough quality protein. An example that is directly related to the Cushing’s discussion is the amino acid, tyrosine. As we’ve just covered, tyrosine is directly involved in the formation of dopamine which is key to regulating the pituitary and adrenal glands. Getting enough quality protein will ensure enough tyrosine. So how do you increase protein quality? First, you want to feed a mix of grass hays, as wide a variety as you can. Grass hays include timothy, orchard, brome, Bermuda, fescue, etc.; in addition, provide alfalfa to add variety to your protein sources. However, keep in mind that since it is high in protein it’s also higher in calories. The underweight horse can have a good amount of alfalfa (no more than 50% of the total hay ration); on the other hand, the overweight horse should probably be limited to no more than two or three pounds of it a day.
Hemp seeds exceeded the quality of both of those[8]. So to boost protein quality, you can add hemp seeds. Depending on the horse’s weight, you can give anywhere from a quarter of a cup to a full cup. They are high in fat so you don’t want to give too much to an overweight horse, but the protein is absolutely wonderful and they taste excellent. (They’re great for you, too, by the way. If you’ve never tasted them, you’re in for a treat—you will really enjoy them.)
Split peas are another good source of protein for your horse. These are the same kind of dried split peas you get in the grocery store to make split pea soup. They come in green and they come in yellow. Either one is fine. You can add them, for example, to soaked beet pulp or to timothy or alfalfa pellets that you add some water to. Let them moisten for a few minutes. Horses love them; about a half cup per meal is a really nice way to give your horse some more amino acids.
For the underweight horse, you’ll want to add even more calories; beyond adding alfalfa, adding more fat is also important. Ground flaxseed would be good for this; you can give an underweight, full-sized horse up to two cups of ground flaxseed a day. Or try chia seeds in the same amount—these are high in omega 3s that are anti-inflammatory. Watch out for inflammatory oils that are high in omega 6s. Remember what we discussed earlier: A horse needs some omega 6s but if they’re out of balance with omega 3s, then you’re promoting inflammation—and you know where that leads: to free radical formation and then oxidative stress, which is, of course, what you want to prevent or reduce. It’s hard to find an oil that’s 100% suitable; all of them contain some omega 6s. Rice bran oil, for example, contains about 30% omega 6s; however, most of its fatty acids come from non-inflammatory omega 9s. Stay away from soybean oil and corn oil. Coconut oil is something you might want to consider but it doesn’t add as many calories as some of the other oils do; furthermore, a horse is simply not used to ingesting medium chain triglycerides such as coconut oil has; it’s not natural to their metabolism so I don’t like to feed coconut oil for too long. Copra meal, by the way, is made from coconuts and it has protein but it’s not very high in quality.
Two Goals, Two Keys to Achieving Them. Our first goal is to reduce oxidative stress, thereby preventing or reducing the destruction of dopamine-promoting neurons and slowing the progression of Cushing’s disease in your horse. Our second goal is to prevent laminitis; as we’ve discussed, all cushingoid horses are candidates for laminitis, more so if they’ve already had one attack or if they are already insulin resistant due to equine metabolic syndrome.
Exercise decreases insulin resistance.