The Low Carb Story
The healthy resting horse can get all required nutrients from good quality hay and/or pasture along with balanced vitamins and minerals, a white salt block, and water. But we all like to feed that extra supplement. So when do we have to worry, and what is safe?

Equine Grain-Associated Disorder (EGAD) is the name given by Dr. David S. Kronfeld of Middleburg Agricultural Research and Extension Center at Virginia Polytechnic Institute and State University to describe common feed-related disorders in horses.

  • Long-term feeding of grains, molasses, and grain mixes with molasses (like 4-way, sweet feeds) leads to insulin resistance and unnatural feeding-fasting cycles of high blood sugar and high insulin in horses. Equine Metabolic Syndrome and laminitis may result.
  • When over three pounds of grain are fed, the rapid fermentation that takes place in the stomach, with overflow into the large intestine, can lead to increased acid production, inflammation of the intestinal lining, and eventually to some forms of gastric ulcers, colic, colitis, diarrhea, and laminitis. Keep in mind that high fiber concentrates can be fed at up to 5 pounds per feeding.
  • In susceptible horses, regular feeding of grain is associated with two forms of tying up or muscle cramping--recurrent exertional rhabdomyolysis and polysaccharide storage myopathy (PSSM). It is now estimated that 6-12% of all Quarter Horses carry the gene for PSSM.
  • In young, growing horses, overfeeding of carbohydrates may promote osteochondrosis (cartilage abnormalities) and flexural deformities like contracted tendons.
  • Overfeeding in general leads to obesity which alone can lead to Equine Metabolic Syndrome (Peripheral Cushing’s Disease).
  • There is also a behavioral "sugar high" associated with feeding cereal grains.
So, the goal these days is to feed a low carb diet--more fiber and added fat.

LOW CARB means low sugar and low starch, but HIGH FIBER
There is good carbohydrate--fiber--and then there is not so good. Starch and sugars are termed nonstructural carbohydrates (NSC). High NSC feeds include cereal grains like oats, corn, and, especially, barley, sugars like molasses, and also fructans, a sugar found in cool season grass in the spring and fall, especially in the afternoons. These carbs are absorbed primarily in the small intestine, or foregut, and are rapidly converted into blood sugar. The good guys--fibers--include hay, pasture, beet pulp, and soybean hulls, and are digested and converted into energy in the hind gut.

Average Percent NSC (Sugar and Starch) Content of Common Feeds
High NSC ("Bad guys")
Corn 71% (28% digested in foregut)
Barley 60%
Oats 53%
Wheat Bran 30.8%
Oat Hay 22%

Intermediate NSC
Soybean Hulls 19%

Low NSC ("Safe guys")
Alfalfa Hay 11.3%
Grass Hay 13.8%
Bermuda Hay 13.5%
Washed, Processed Beet Pulp 12.2%

Gastric Ulcers in Horses
Because the horse has a relatively small stomach and constantly produces digestive acids that pool at the bottom, any increase in pressure on the stomach or increased production of acid tends to cause ulcers in the upper portion of the stomach. Increased feeding of grain, feeding large meals twice daily, transportation, excitement and exercise, and stress can increase the incidence of stomach ulcers. "66% of a diverse group of horses had gastric ulcers," as well as 93% of race horses in training. Horses evolved to eat frequent small meals, 14 or more hours daily. Horses on pasture rarely have ulcers. Horses should never go more than 12 hours without hay or grass.

Fructan, the sugar in "grass founder"
Cool season grasses like brome, orchard grass, timothy, fescue, and Kentucky Bluegrass grow best in cool sunny weather, but when it gets too cold these grasses store a sugar molecule called fructan rather than using it to grow. If a horse is susceptible to laminitis, commonly known as founder, grass pastures are the most dangerous during the spring and fall, in the afternoon, and after a frost, Ideally, grass hay should be cut on a cloudy day, in the morning, before the fructan content of the hay is increased by photosensitization. Fertilizing and irrigating grass pastures encourages grass to grow and increase protein content rather than store fructan.

Horses prone to laminitis should have very limited access to grass, and only in early morning hours. After the first fall frost, they should be kept off of the pasture completely because fructans is increased in frost damaged grass.

Common Causes of Digestive Colic in Horses
  • Sudden diet changes, including a new delivery of a different cut of hay from the same source.
  • Confinement, especially sudden confinement as after injury or surgery
  • Poor quality forage
  • Low forage intake--minimum forage should be 1% body weight daily
  • Over-consumption--usually of grains
  • Rapid intake of feed due to competition with others
  • Inadequate water intake
  • Inadequate salt intake
  • Inconsistent feeding schedule or feedings more than 12 hours apart
  • Dental disease
  • Parasite infestation
Nutrition Advice
  1. Avoid high carbohydrate feeds such as "sweet feed," molasses, corn, and barley, "4-way"
  2. Laminitis-prone horses should not be pastured on cool season grasses after a frost, or during cold weather, especially during spring and fall. Pasture grasses contain the most fructan in the afternoon. Limit grazing to morning only.
  3. Feed high fiber, higher fat concentrates with a quality protein supplement when needed for energy or growth in working or growing horses. Couch potatoes just need vitamins and minerals.
  4. Increase the frequency of feeding to help reduce most feed related digestive disorders in horses.
  5. Keep exercise consistent, frequent, and event specific for muscle training and bone strengthening and to reduce the incidence of impaction colic.
  6. Typical livestock trace mineral blocks are 95% or more salt and are deficient in most minerals needed by horses. Mineral blocks designed for horses should be used and are available, or a granular vitamin/mineral supplements can be added to daily concentrate ration.
  7. Concentrates and hay should be weighed. Ration calculations are based on analysis of hay and any added concentrates . Labs available to analyze rations including NSC Equi-Analytical Lab 1-877-819-4110
  8. How much to feed? On average 1.5% of the ideal body weight total. For a lot of Quarter Horses, that is too much. Remember to increase hay 2 pounds after 7 pm on nights where temp will be under 10 degrees, 2 more pounds if below zero. Remember to add 1/2 pound of your horse’s concentrate for every two hours of moderate exercise.
  9. Alfalfa hay should not be fed free choice because it contains too much protein and the calcium to phosphorus ratio is too high.
  10. Most hays are deficient in phosphorus, sodium, copper, zinc, manganese and iron.
  11. Selenium content of feeds varies greatly from region to region. Hays should be analyzed for selenium content. Too much or too little selenium can cause clinical diseases.
  12. Free choice white salt blocks should always be available
See Also:   |   Colic Handout  |   Laminitis  |   Low Carb Products in the Pagosa Springs Area  |  

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