In general, hormones derived from the two classes of essential fatty acids have opposite effects. Those from omega-6 fatty acids tend to increase inflammation (an important component of the immune response), blood clotting, and cell proliferation, while those from omega-3 fatty acids decrease those functions.
Since Omega-6 fatty acids have been suspected to contribute to joint inflammation and scientists are finding that Omega-3 fatty acids reduce inflammation in humans, researchers at Michigan State University theorized that they might find a difference between horses supplemented with both, and scientists at Texas A&M studied the possibility that, like in humans, Omega-3 fatty acids would reduce inflammation. Both group of researchers conducted controlled studies that made the case that, for joint health, horses should be supplemented with oils rich in Omega-3 fatty acids, not Omega-6.
From an article published by Kentucky Equine Research (KER):
Researchers at Michigan State University theorized that, if the same effect was found in supplemented horses, minimized discomfort might manifest as increased stride length among horses suffering from joint stiffness. To test this theory, they measured stride length at the walk and trot for 18 Arabian horses (12 mature animals and 6 two-year-olds). Horses were paired and all horses were fed sweet feed and Timothy hay. One horse in each group was supplemented with fish oil for 75 days while the other was given corn oil to supply an equal number of calories. The horses were exercised five days a week under saddle, on a longe line, or on a free-flow exerciser. At the conclusion of the trial, plasma levels of omega-3 fatty acids were higher in the fish-oil-supplemented horses than in the corn-oil-supplemented horses. There was no change in stride length at the walk, but horses supple- mented with fish oil tended to have an increased length of stride at the trot.
The beneficial effect of omega-3 fatty acid supplementation for horses with arthritis was confirmed by a study performed at Texas A&M University. The experiment measured the effect of feeding supplemental omega-3 fatty acids on indicators of joint inflammation in plasma and synovial fluid in horses that had been previously diagnosed with osteoarthritis. Sixteen mature horses with arthritic knee, fetlock, hock, or stifle joints were divided into two groups, one of which was a control. In the other group, horses were supplemented with two pelleted omega-3 sources for 90 days. Samples of blood and synovial fluid were collected periodically during the trial period. Supplemented horses showed lower levels of joint inflam- mation indicators (white blood cells in synovial fluid and fibrinogen and prostaglandin E2 in plasma) than the control group. The researchers said, “The inclusion of omega-3s has the potential to benefit geriatric horses with osteoarthritis, as well as performance horses subjected to high-impact and high- stress training, thus potentially improving quality of life and athletic performance."
In 2009, I switched my off-the-track Thoroughbred, Jazz, from corn oil to black oil sunflower seeds. Corn oil is commonly used in my barn for weight gain and to improve the appearance of the horses' coat, but the negative news about joint inflammation prompted me to make the switch. At the time, I knew that flax seed oil or flax seeds, which are rich in Omega-3 fatty acids, would be better, though I wasn't aware of mounting evidence showing that Omega-3 fatty acids could reduce inflammation. However, I was under the impression that the flax seeds needed to be grounded and that, once ground, would be unstable and quickly spoil. I should have dug a little deeper at the time, because since then I found that the seeds can be fed whole and that any whole seeds that pass through in the horses' manure are mostly just the hulls. Just last week, I ordered a 50-lb bag of whole organic flax seeds.
For a simple synopsis on Omega-3 vs. Omega-6 fatty acids and what to feed or avoid, check out this table originally published on SmartPak's blog in a post titled, "The Truth about Feeding Horses Corn Oil". Disclaimer: the article doesn't link or give the sources for the numbers in this table.
|Feed||Omega 6:Omega 3|
|Commercial, fortified grain||8:1|
|Whole grains: oats, corn, barley, wheat, rice||24:1|
|Vegetable oils: corn, sunflower||87:1, 199:1!*|
|Vegetable oils: canola, soybean||3:1, 7:1|
|Flax seed||1:4, good|
|Fish oil (includes the specific Omega 3s EPA & DHA)||Virtually all Omega3!|
* The ratio for sunflower is for the pressed oil, not seeds, as I have been using.
So the take-home message is that cheap and accessible corn oil will probably make your horse shinny and he'll gain weight, but will also contribute to joint inflammation, while oils and feed rich in Omega-3 fatty acids will actually do the opposite.