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Conditioning the thin horse

Marcia Hathaway, PhD, University of Minnesota; and Ron Genrick, Assurance Feeds

Before establishing a feeding regimen for the thin horse, it is important to determine why the horse is thin in the first place.

It is rare to see a healthy horse that is too thin. Before establishing a feeding regimen for the thin horse, it is important to determine why the horse is thin in the first place. If the basis for weight loss (or the inability to gain weight) is not established, the thin horse may be put in an adverse health situation.

It may be that the horse is simply not receiving enough calories. If so, the problem can easily be eliminated by offering more calories. Some options are:

  1. allow access to pastures for a longer period of time;
  2. offer more hay or higher quality hay;
  3. offer a grain ration, or;
  4. offer a high fat supplement (e.g. rice bran) along with the grain.

Some horses' temperament may be affected by the increased feeding of carbohydrates and sugars contained in grain rations. If this is the case, the grain ration should contain 6% fat or more, or offer a high fat supplement. Make sure that the supplements contain adequate vitamins and trace minerals.

Whatever changes are made should be made over a two week period to allow adequate time for the intestinal tract time to adjust to the change. Feed for a weight gain of 0.5 to 0.75 pounds per day. If a horse's weight is stable, 3 to 4 pounds additional grain ration will produce this gain. The table below may be used as a guideline.

  Maintenance Light work Moderate work Heavy work
Grass hay 20 lbs 20 lbs 21 lbs 22 lbs
Grain ration 4 lbs 6 lbs 9 lbs 12 lbs

Table adapted from 2007 Horse NRC.

If inadequate calories are not causing the horse to be underweight, consultation with a veterinarian, farrier and nutritionist is recommended to uncover underlying factors. Other causes might include:

  1. Age. Older horses are more timid, subjected to intimidation by more aggressive horses, need more time to eat and drink, and often eat slowly and need periods of rest between meals. Separation from the herd may be necessary to insure adequate feed and water intake. Their teeth may be worn or missing so chewing forage is difficult. Higher calories, added fat with higher levels of protein, vitamins and mineral are necessary. Senior horses may require a special complete feed that includes forage.
  2. Health. Metabolic issues, disease and other health conditions such as laminitis, founder, gastric ulcers, parasites, cribbing, dental issues, digestive tract problems, and chronic pain may prevent horses from consuming enough calories.
  3. Environment. The pecking order will affect horses on the low end; as they may not have adequate access to hay, feed and water. Horses prefer water between 45° and 65° that is fresh and clean. Proximity is important; there is a limit to how far a horse will walk for water. If water intake is low, feed intake will also be low. Stall walking, weaving and fence pacing will burn calories requiring more hay or grain. During the summer months, horses may not have adequate grazing or eating time due to bothersome insects. Insecticides and protective sheets will help.
  4. Climate. As the temperature and humidity increase, feed intake drops. Body heat is created in the digestive process, particularly from hay and pasture because of the higher fiber amounts found in forage compared to grain. Because of this, it is natural for horses to ingest less forage during hot stretches. Offering hay in the cooler times of the day can help. Feeding additional grain during hot stretches may be required to meet caloric needs of underweight horses.

Conversely, more hay is required in the winter to keep the horse warmer. In more severe winters, extra grain may also be required. All horses have a low critical temperature (LCT) threshold; which is approximately 18°F. The LCT is not the same for all horses. For example, growing horses not yet acclimated to a climate, horses arriving from a warmer climate, and older horses area usually less tolerant of colder weather. For each 10° drop below the LCT, a horse requires a 1% increase in energy or approximately 2 pounds hay. The range in additional calories required by more sensitive horses can range up to 33 to 50%. The additional calories should first be met by offering more hay than grain (forages are higher in fiber compared to grain).

Wind and precipitation have an enormous effect on the horses' body temperature. Steps should be taken to keep blankets and hair coats dry. Wet horses in the presence of wind will have trouble keeping warm and may lose weight. Windbreaks, shelters and blanket will help; as will a body condition score of six to seven going in to late fall if limited or no shelter is (or will be) available.

All horses should be checked weekly for body condition, health issues, and injuries.

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