The Thoughtful Horseman: Equine Nutrition Facts & Myths

A lot of people tend to think of bermuda hay as the iceburg lettuce of horse forages: bland, nutritionally lacking, and no horse could possibly get fat on it! If you haven't been cornered by me long enough to hear what I have to say on that subject, you're probably nodding your head..."yup," you're saying, "just like rice cakes for horses, right??"

First of all...don't ever make the mistake of thinking you can feed bermuda free choice with no danger of a fat horse! Quite simply, it provides ample energy for the average horse in moderate work. If you're concerned that your horse needs more hay so that he has some to last the whole day, there are better approaches than overfeeding. Slow feeders are all the rage in the more forward-thinking horse care circles right now. Slow feeders provide benefits beyond merely creating a more natural pattern of food in the gut, including keeping boredom at bay.

A look at averages from accumulated crop years from 2000 though 2008, as well as dozens of local samples, shows that bermuda is actually quite suitable for most horses. Of course, no hay will supply optimum amounts of all trace and major minerals, fatty acids, and vitamins. But overall, bermuda is easy to balance, and generally lower in non-structural carbohydrates than most other grass hays.

What about protein? A 1000lb (454kg) horse needs 572g of protein per day, with 19g lysine. Based upon an 18 lb daily ration, our averaged bermuda would supply 818g protein, and 19g lysine...perfectly adequate. While additional protein is sometimes touted for weight gain, protein is an inefficient energy source compared to other options. It causes the horse to form larger quantities of urea, which then necessitates consumption of more water to excrete the urea. And increased risk of dehydration is associated with protein levels exceeding 10% in horses in strenuous work (endurance horses, eventing). Increased protein levels and elevated risk of metabolic failure have also been linked.

There is some debate that Coastal Bermuda may present an elevated risk for impaction colic, but current research on the subject shows conflicting results, and adequate water intake appears to mitigate the risk. It is widely assumed that the risk of impaction is due to low moisture and fibrous, fine stems, but again, this is conjecture. Some evidence suggests that an allergy to Coastal Bermuda may cause inflammation which in turn leads to the impaction. It's important to note here that not all Bermuda is Coastal Bermuda...there are many varieties, and only the Coastal Bermuda seems to be implicated here. If you're worried, ask your supplier or grower what variety they use.

All things considered, bermuda may be the best option for most horses in the southern states.

Alfalfa

Alfalfa, long a mainstay in the equine diet because of its wide availability for cattle forage, is linked to the formation of enteroliths (stones) due to high phosphorous content. Research suggests that enteroliths are more prolific when the digestive tract is high in phosphorus and high pH.

While alfalfa is generally lower in NSC than most grass hays, the type of starch in alfalfa is more readily converted to glucose, and therefore creates a greater amount of insulin in response, making it unacceptable for horses with insulin resistance issues, or laminitis.

Alfalfa is exceptionally high in protein: anywhere from 15% to 20%, compared to the 10% to 11% suitable for horses. The extra protein is sometimes touted for weight gain, but there are more appropriate and efficient ways to add energy to the horse's diet.

Corn Oil

Corn oil has become popular as cheap way to add fat calories to the diet. It has also been touted as a preventative for ulcers and gastritis, and as a buffer when feeding bute.

High fat/oil intake also has the potential to interfere with fiber fermentation. Fat which escapes digestion in the small intestine can have a negative effect on the numbers of microorganisms in the large bowel, and on fiber digestion. Studies differ in their conclusions about how much is too much, and the ceiling for fat digestion in the small bowel has not been determined. However, diets containing over 15 to 20% fat are generally considered to have the potential to negatively affect hind gut function.

In some situations, fat feeding is appropriate. Horses with EPSM or PSSM generally do best when fed fat.

The research done on the effect of corn oil on general ulcers/gastritis in horses is conflicting, and therefore doesn't highly recommend it. For every study that found a marginal protective effect, another negated the finding.

Corn oil to prevent the detrimental effects of bute? Simply not true. Bute impacts the hindgut. Because horses digest fat extremely efficiently, oils are almost 100% digested and absorbed in the small bowel and never make it to the hind gut.

If you must feed corn oil, use NO MORE than 4 to 6 oz. per day, EVER, and then only as a last resort for horses in dire need of calories when other options are simply not available.

Cider Vinegar

It's long been believed that a cup of apple cider vinegar given orally once a day over grain or forage is a valid way to prevent enteroliths (intestinal stones) in horses by raising the acidity in the colon. However, the efficacy of this remedy has never been documented.

One of the potential problems with feeding cider vinegar is that it can enhance iron absorption by increasing acidity in the gut. (Incidentally, adding vitamin C to the horse's diet can have the same effect. Horses very effectively produce their own vitamin C, and it is not usually something that needs to be added.) Most of our domestic horses are already ingesting far more iron than they need, and have no way to excrete the excess. The excess iron can cause myriad metabolic issues. A better solution to preventing stones? Stop feeding straight alfalfa, and avoid feeding large quantities of wheat bran.

Glucosamine

Glucosamine in combination with chondroitin sulfate offers a documented protective effect for joint health. It's important to understand that the two together have been shown to work better than either substance alone. This combination is a good choice for horses with degenerative joint disease.

While research on glucosamine supplementation in horses is scarce, research in other species has demonstrated a link between glucosamine and insulin resistance. Until recently, the link was thought to be related to intravenous and intramuscular glucosamine only, but a study published in 2007 showed the same effect with oral glucosamine. In horses with insulin resistance, laminitis, or Cushings disease, glucosamine in any form is contraindicated.

Garlic

The idea that garlic might be an effective insect repellent has long been popular for dogs and cats. Now horses are alienating their herdmates, if not the insects, with their garlic breath. The effectiveness of feeding garlic is limited at best, and, like onions, garlic can actually be dangerous for horses. Adding garlic has been shown to cause Heinz Body Anemia in horses. Garlic may be undesirable for horses with insulin resistance, as well. Some studies have shown certain garlic extracts lowering insulin, but others have shown an increase in insulin.

Cinnamon

Cinnamon has been shown to reduce blood sugar in some horses. While it has not been conclusively shown to reduce insulin levels, it seems to have become a popular practice amongst owners of Cushings horses to feed cinnamon. It is so effective at lowering blood sugar, though, that it can actually be dangerous...as little as a tablespoon can cause blood sugar levels below what is healthful. Cinnamon should ONLY be used to lower blood glucose levels, NOT to lower insulin levels.

Rice Bran

Brans in general are very high in phosphorous, and rice bran is no exception, although it is not as phosphorous rich as wheat bran. If you are feeding a high-calcium diet, rice bran can be a good choice for adding phosphorous and magnesium to balance the calcium. However, many of the rice bran products available for horses have calcium added to balance the high phosphorous in the bran.

Rice bran is also typically quite high in non-structural carbohydrates (NSC), averaging between 17 and 25%, and is therefore not recommended for horses with insulin resistance issues, laminitis, or Cushing's disease. Still, it is lower in NSC than wheat bran, which averages 22 - 29%, making it a better choice unless your goal is to really boost phosphorous.

Rice bran can be an easy, economical way to add dense calories without adding as much sugar and carbs as grains. Just be sure to consider the calcium/phosphorous/magnesium balance, and don't feed rice bran to horses with insulin resistance, laminitis, or Cushing's.

Ground Flax Seed

Flax has become very popular recently. Rumors have begun to circulate about the alleged dangers of flax; one of these refers to a precursor to cyanide that is present in raw ground flax. While the ground flax does indeed contain cyanogenic glycosides, the horse's stomach acid renders them harmless. Flax is actually quite safe for horses. Ground flax seed provides omega 3 fatty acids that hay lacks, but that are necessary in the horse's diet. There is even evidence suggesting that omega-3 fatty acids may be beneficial for horses with Cushings disease, and may enhance fertility. Omega-3 fatty acids have an anti-inflammatory effect as well, and may help horses prone to exaggerated allergic reactions.

Yucca

Yucca seems to be cropping up in a lot of supplements these days. A search for "yucca" on SmartPakEquine.com yields 31 different products, ranging from joint supplements to anti-inflammatories to weight builders. While it does indeed have anti-inflammatory properties, yucca's corticosteroid effect can mimic or exacerbate insulin resistance and Cushing's disease. It is not recommended for horses with laminitis, insulin resistance, or Cushings.

Facts & Myths

Bermuda Grass Hay