Feeds and feeding to prevent acidosis in horses

Horses require digestible energy (DE) both for maintenance of body functions and for performance. Most hay and pasture can provide sufficient DE for maintenance, and low levels of activity, however horses cannot eat enough of these feeds to provide energy for higher levels of performance. For most performance horses, it is necessary to feed a high DE feed to provide the extra energy. Most traditional energy feeds are based on grain or grain based by-products which contain non structural carbohydrates (NSC), i.e. sugar and starch. Overfeeding of these feeds, coupled with under work is the major cause of many of the metabolic disorders including laminitis, colic, EMS and fizzy behaviour.

To avoid acidosis, select feeds with a balanced profile of non NSC (oil and fibre), and NSC (sugar and starch) energy.

The Stance Equine Feeding System outlines several feeds suitable for horses with, or to avoid acidosis. These include

CoolFibre contains a low NSC (7%), high level of digestible fibre, and MCT for gut health, and can be used to dilute high NSC grain based feeds.

CoolStance contains <12% NSC, which reduces the amount of fermentable sugars and starch that are fermented to produce acidity.

CoolStance and PowerStance contain MCT in the coconut oil, which are thought to control excessive growth of intestinal organisms, which can produce acidsthat lower the pH of the gut.

What is Acidosis?

Horses have a limited capacity to digest starch in the stomach and intestines. Feeding too much starch can "overload" the digestive capacity in the intestines and the excess starch will flow undigested to the hind gut, where it is fermented by the microbial organisms that live in the hind gut. These organisms normally produce volatile fatty acids (VFA) that are used by the horse for energy. When high NSC feeds are fed, excess amounts of starch can flow into the hindgut, and the organisms can produce lactic acid. The lactic acid causes a rapid decrease in pH (<4), i.e. increased acidity or acidosis, which is the same as occurs in feedlot cattle.

The rapid decline in pH causes death of the microbial organisms, release of microbial toxins, and reduced fermentation in the hindgut. These conditions can lead to laminitis and colic, and reduced appetite, and deficiencies in B Vitamins.

Symptoms of Acidosis

Feet problems such as lameness, laminitis ( founder), ringbone or navicular disease

Tail rubbing due to the level of acidic material in the droppings causing irritation

Loss of appetite and diarrhoea

Rancid smell from droppings due to the amount of dead microbial flora being passed

Mouth problems such as sores (mouth ulcers)and teeth sensitivity (evident when eating hay)