The benefits of feeding oil
Many of us now add oils to our horses’ diets. DR CLARISSA BROWN-DOUGLAS explores the benefits and explains why not all oils are created equal.
Adding oils to your horse’s diet is common practice these days. There are lots of oils available and the market is flooded with choice. Vegetable oil, canola, rice bran, corn, soy, flaxseed, fish oil … so how do you decide what oil to use? And are all oils the same?
Why add oil to your horse’s diet?
Oils are a source of fat which can be used in a horse’s diet to improve performance, maintain weight, improve coat and skin condition, improve behaviour, reduce inflammation, or increase the energy density of the diet. Oil is especially useful for hard working horses that need a high energy diet and yet often have limited appetites. A concentrated energy source, oil allows for a lower grain intake for weight maintenance, or increased body condition in a spelling horse, show horse or a yearling being prepared for the sales.
We often view oil as a foreign ingredient for horses when this is not necessarily true. There is actually a small percentage of fat in the basic horse diet of pasture grasses (1-4%) and even in the modified diet of oats (4-6%) and hay (1-3%), so adding oil to their diet is not completely contrary to the way their digestive tract has evolved. Research has shown that horses can tolerate up to 20% of their diet as fat, although in practice, this much is rarely fed and high oil content often reduces palatability of a feed.
Fat is an important part of the diet for all horses. It facilitates the absorption of fat-soluble vitamins A, D, E and K, and is a source of the essential omega-3 and -6 fatty acids that are linked to inflammatory response. In addition to their effects on inflammation, omega-3 and omega-6 fatty acids aid in the maintenance of cell membrane stability, the development and function of central nervous system tissue, bone development, oxygen transfer and immune functions.
A slow energy source
There are numerous benefits to including oils in the diets of performance horses, especially ones exercising for long periods of time, or those that are prone to being reactive. Fat as an energy source is utilised during periods of long, slow work and is released gradually over time. The slow-release energy that fat produces can improve undesirable behaviour in many horses. Because oil is metabolised slowly and does not cause a spike in blood sugar, it is viewed as a ‘calm’ or ‘cool’ source of energy – great for those hotter horses who don’t do well on cereal grain. Oils are also a safe energy source for horses that are intolerant to cereal grains, including those with muscle myopathies including tying up and PSSM, and also those with gastric ulcers, PPID (Cushings) and laminitis.
Adding a source of fat to the diet also has an additional benefit: if fed over a long period of time, horses can switch to utilising it as their predominant energy source and adopt glycogen-sparing properties, and therefore spare muscle and liver glycogen for use in high intensity exercise. For horses working over long periods of time, such as those competing in endurance or eventing, this is an invaluable tool. To fully utilise this mechanism, 8-10% of the diets of performance horses should consist of a fat source such as oil or stabilised rice bran.
Feeding oils has also been found to increase the amount of oil in the horse’s skin and most horse owners know that feeding a little oil will give their horse a sleek and shiny coat.
What oil do I choose?
Although oils contain the same amount of energy by weight, they vary widely in their composition and benefits to the horse.
Oils are made up of fatty acids joined together in different length chains. Researchers have focused their attention on two distinct types of fatty acids, the omega-3 family and the omega-6 family, because of their involvement in body inflammation. Omega-3 and -6 fats are considered essential fatty acids because they must be obtained from dietary sources. In contrast, omega-9 fatty acids can be produced by the body, and are therefore not considered essential. In general, omega-3 fats are linked with resolving inflammation, whereas omega-6 fats are pro-inflammatory.
Many of us eat fish regularly or take fish oil supplements, and fish oil continues to gain popularity as an equine nutritional supplement, benefiting an array of body systems and organs. This benefit comes specifically from the long chain omega-3s known as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). These are the biologically active omega-3s that research has shown to have many health benefits in mediating and resolving inflammation in people and also for horses (Table 1).
Modern equine diets tend to provide a skewed ratio of omega-3 and omega-6 fatty acids, underproviding omega-3s and oversupplying omega-6s. Grains and premixed feeds, as well as many vegetable oils including corn, soy, rice bran, and copra are high in omega-6s, while hay and pasture provide short chain omega-3s despite being low in total fat content. Canola oil has an adequate short chain omega-3 content, although still lower than the amount of omega-6 it provides.
Flaxseed oil (also known as linseed oil) contains short chain omega-3s (ALAs), which must then be converted to DHA and EPA in the body, but this process is very inefficient and studies have shown that flaxseed or vegetable oil does not lead to an increase in EPA and DHA levels in tissues (links to the study results are provided at the end of this article). For this reason, finding a source of dietary EPA and DHA from marine derived oils is recommended for increasing the biologically active omega-3 fatty acid levels in the body.
How much oil and how to feed it?
Oil should be used as a supplement and not as the basis of the horse’s diet. The horse must still have an intake of 1.5% of its body weight in fibre to ensure a healthy digestive tract, adequate protein, and balanced vitamins and minerals. For energy and conditioning, added oils can make up to 10-20% of the total energy in the diet
During digestion, fat is broken down into its most basic structures, fatty acids. An increase in the amount of fat fed will therefore create an upsurge in circulating levels of fatty acids. Fatty acids are prone to oxidation, the byproducts of which can be harmful to cells. As a result, nutritionists typically recommended that an antioxidant such as natural vitamin E be supplemented when a diet is high in fat.
If you’re purchasing a commercial feed, check to ensure that the fat content is listed on the bag label. In general, a higher percentage of fat will indicate a higher energy feed. High fat feeds for horses are those with more than 8% fat, usually from added vegetable oil, or high fat ingredients such as rice bran, soy, sunflower seeds, copra, or flax.
If you want to add oil-based calories to your horse’s diet, feed canola oil, flaxseed oil, or stabilised rice bran. Recommended intake varies, but adding a cup of oil or 250g to 1kg of stabilised rice bran is common for added calories. However, if you want the health benefits of long chain omega-3, you only need to supplement with 30-60ml of fish oil per day. Fish oils are fed at lower daily intakes than oils fed principally for energy.
Feeding fat can be a valuable addition to your horse’s diet, so if you think your horse could benefit from a boost in topline, an increase in stamina, a shiny coat, and calm behaviour add a source of oil, and consider the addition of long chain omega-3 fats from fish oil.
To learn more about the research into the use and value of oils in a horse’s diet, follow these links: Colorado State University, University of Florida and Kentucky Equine Research.
For a tailored diet analysis or advice on optimising nutrition for bone health, contact Kentucky Equine Research at advice@ker.com, and for information on all topics related to equine nutrition visit Equinews™.
