Mary Allen
Oil provides horses with a lot of energy, can support shedding, and help with metabolic diseases and inflammation. But be careful: too much oil makes horses sick.
Among horse feeds, oil is a kind of super fuel. One liter delivers an average of 38 megajoules (MJ), far more than a kilogram of hay with around seven MJ or oats with eleven MJ. If a horse already weighs too much or already suffers from Equine Metabolic Syndrome with chronic laminitis, this is a problem. In such cases, oil should not be fed at all or – in consultation with the veterinarian – only in very small quantities.
For sport horses that are subjected to a lot of stress under the saddle or in front of the carriage, oil is interesting as an additive to meadow hay and grain precisely because of its high energy density. “Horses have a limited absorption capacity for the dry feed substance, which is around three percent of their body weight,” says Michaela von Zerssen, animal health practitioner and feeding consultant. She often hears the argument that horses in the wild would not suck on the oil bottle either. That’s true, of course, but free-roaming horses with appropriate vegetation have access to species-appropriate feed and are not ridden.
Little Space in the Digestive Tract
The expert gives an example: An eventing horse weighing 600 kilograms that are subjected to a lot of stress needs around 140 MJ of energy per day. With 18 kilograms of very good quality hay, it receives a maximum of 126 MJ of energy. Due to its intensive training, however, it has neither time to eat this nor does this amount make sense from a metabolic point of view. On the contrary: Neither the desired performance nor the muscle-building can be achieved. Even if part of the hay is replaced with concentrated feed, the energy requirement is not yet covered.
In addition to energy, oats, muesli and the like also contain a lot of carbohydrates and proteins, which have undesirable side effects in excessive doses. Oil, on the other hand, takes up little space in the digestive tract, contains a lot of energy, but neither carbohydrates nor proteins. This makes it the ideal additional feed for sport horses as well as for animals with stress myopathies (cross-strap) or the muscular metabolic disease PssM (polysaccharide storage myopathy) since products with a high carbohydrate content should be avoided in both diseases.
However, oil should be dosed relatively sparingly on all horses so that it does not cause any damage. Because a horse does not have a gallbladder, which could excrete the bile secretion in bursts when fed with fat, and thus has limited digestion of fat. “In horses, around 1.5 to 2.5 deciliters per hour of bile, which is formed in the liver, drips continuously into the approximately 20-meter-long small intestine below the stomach outlet,” says von Zerssen. “But if the horse takes in more oil than it can digest in the hour and a half in the small intestine, it inevitably ends up in the large intestine.” And with the help of bacteria, it breaks down the structural substances and other undigested nutrients to gain energy but is not designed for oil digestion.
Oil in the large intestine disturbs the bacterial colonization of the intestine and thus also the digestion of crude fiber. The consequences include unpleasant flatulence. To avoid this, the switch to high-fat feeding should be done very gradually over at least two weeks. During this time, it makes sense to pay more attention to the condition of the feces and digestive problems.
Two Important Fatty Acids for Horses
The absolute upper limit is one gram of oil per kilogram of horse per day. “In the case of the example horse given, that would be a maximum of 600 grams of oil, which should be divided into at least three meals because of its digestibility,” says von Zerssen.
In very few cases, however, is it necessary or sensible to feed as much oil as the horse can just about tolerate. Since the optimal dosage depends, among other things, on the state of health of the respective horse, its nutritional status, posture, and training intensity, you should seek good advice before reaching for the oil bottle.
Two fatty acids are particularly important in horse feed: linolenic acid, an omega-3 fatty acid that is also found in small amounts in grass and hay, and linoleic acid from the omega-6 fatty acid group, which is Example is part of the grain. Omega-3 fatty acids fight inflammation, are good for the brain, and stabilize hormone levels. Omega-6 fatty acids are, among other things, components of cell membranes and promote growth and repair processes. We know from human medicine that the ratio of the two fatty acids plays an important role since otherwise they mutually inhibit each other’s positive effects.
Suitable Types of Oil
There are no detailed studies on this subject for horses. “Since horses mainly ingest omega-3 fatty acids when grazing, horses that are fed concentrated feed and thus a lot of omega-6 fatty acids should choose an oil type with a high omega-3 content,” recommends von Zerssen. Linseed oil is rich in linolenic acid, but it spoils quickly and should therefore be stored in a dark and cool place. Also suitable are milk thistle oil, hemp oil, black cumin oil, salmon oil, and rice germ oil.
Some of these oils are said to have therapeutic effects depending on the vitamins and secondary ingredients they contain. Black cumin oil helps with diseases of the upper respiratory tract and allergies. Rice germ oil supports muscle building due to its high content of tocopherols and gamma-oryzanol. A consultation with the veterinarian or feeding experts will help with the selection. However, the horse has a say in the selection, as von Zerssen emphasizes: “The best recommendation is useless if the horse has an aversion to a certain oil and refuses to take it.”