carbohydrates | Horse Racing Free Tips

Ask the Expert: Fall Grazing

Owners and caretakers of metabolically challenges horses are often aware of the health hazards ingesting lots of fresh, spring grass can bring on their charges, but grazing horses on lush pastures in the fall is fraught with its own set of perils.

Frost damaged pastures can have higher concentrations of nonstructural carbohydrates, leading to an increase in the potential for founder and colic, especially in horses diagnosed with or prone to obesity, laminitis, Cushings disease and Equine Metabolic Syndrome. To help prevent these health issues, at-risk horse owners should wait up to a week before turning horses back onto a pasture after a killing frost. Subsequent frosts are not a concern as the pasture plants were killed during the ﬁrst frost.

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Why do nonstructural carbohydrates increase during the fall? During the day, plants carry out the process of photosynthesis. In this process, they make carbohydrates as an energy source for the plant. A second process, respiration, is carried out when the plants use up the carbohydrates they produce during the night for energy. Plant respiration slows down when temperatures are near freezing. As a result, the plants hold their carbohydrates overnight. Freezing can stop respiration and lock the carbohydrates in the plant for over a week. Thus, plants tend to contain more carbohydrates in colder temperatures or after a frost. Often, horses will prefer forages after a frost due to the higher carbohydrates levels.

The Hindgut: Understanding Its Role In Equine Digestive Health

Horses rely on fermentation for optimal digestion of feedstuffs and energy production. Hindgut digestion, which occurs in the cecum and large colon, progresses most efficiently when horses are allowed continual access to forage and limited access to feedstuffs that could upset the pH of the cecum, including large grain meals.

Fermentation is achieved through the machinations of billions of protozoa, fungi, and bacteria. Together, these microbes convert carbohydrate-based contents, essentially plant-based fiber, into volatile fatty acids (VFA), which provide energy to the horse. If soluble carbohydrates, such as those found in large supply in grain meals, find their way into the hindgut, some lactate might be produced.

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An overproduction of lactate can shift the pH of the hindgut to a more acidic state, which may cause problems. When a drop in pH occurs, called hindgut acidosis, some of the beneficial fiber-digesting microbes die off. Digestive efficiency drops as a result. In many horses, this manifests as poor appetite, crabby disposition, recurrent colic, and onset of certain stable vices, such as stall-walking and cribbing.

To offset this, horse owners should scrutinize feeding management. Hindgut acidosis is rarely caused by what is fed but rather how it is fed. Here are three strategies to ward off hindgut acidosis:

Good-quality forage should be offered at all times, so the hindgut is continually in “processing mode.” Forage may be pasture, hay, or hay-based products such as cubes or pellets. Forage selection should be based largely on the nutrient needs of the horse.
Concentrate meals should not exceed approximately a half-pound per 100 pounds of body weight (5 pounds for a 1,000-pound horse).
If a horse requires more than 5 pounds of concentrate per day, divide total daily allotment into separate meals. Feeding three or four concentrate meals, evenly spaced throughout the day, is more beneficial to the horse than huge meals.

Some horses, especially those that are asked to perform intense exercise, must consume large grain meals to fuel performance. Hindgut acidosis can be curbed by feeding EquiShure, a time-released buffer that raises the pH of the hindgut and eliminates signs of acidosis.

Diet And Exercise Key To Managing Tying Up From PSSM

Polysaccharide storage myopathy (PSSM) is a glycogen storage disorder in horses that causes muscles to cramp. It occurs primarily in horses with Quarter Horse bloodlines, like Paints and Appaloosas, but it can also occur in draft horses, draft crosses and Warmbloods.

In normal horses, insulin goes from the blood and is stored as glycogen in the muscle and liver cells. In horses affected by PSSM, a large amount of sugar (glycogen) is stored in the muscle and up to four times the typical amount of polysaccharide (an abnormal form of sugar) accumulates in the muscles.

Horses with PSSM are generally in good weight and have a quiet temperament. They often experience a PSSM episode when they begin training or go back into training after a layup, when their movement is restricted. The episode normally comes on after the horse has been walking and trotting for about 20 minutes.

When a horse has a PSSM episode, their muscles get very stiff and hard, especially over their hindquarters; they will sweat profusely, refuse to move, and their flanks may tremble. When they stop moving, the horse may stretch out as if urinating. Foals with PSSM often show signs of muscle pain and weakness when they have diarrhea or an infection like pneumonia.

Horses that have PSSM should not be fed sweet feed, wheat, oats, barley, molasses or feeds high in starch. They should also be exercised daily. Exercise encourages the body to use glucose properly and improves energy metabolism in skeletal muscle.

Researchers have found that if horses have only their diet adjusted, about 50 percent will improve. If both diet and exercise are adjusted, more than 75 percent of horses with PSSM will have few or no tying-up episodes. Though it may seem counter-intuitive, horses should be turned out and encouraged to move as soon as a PSSM episode has dissipated.