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Rice Bran Oil: Facts and Benefits

April 2017 by Tania Cubitt, PhD, HyGain,

Many surprising benefits have been attributed to the addition of fat to the equine diet and there are many oils available to the consumer - canola, maize, soybean and blends of these to name a few options available. 

All have similar levels of energy and omega essential fatty acid profiles. Rice bran oil, in particular, has become quite a sought after product; not only for its high-energy value and essential fatty acid content, but also as rice bran oil is one of the few natural sources of gamma-oryzanol and ferulic acid.

Rice bran is the outer brown layer of the rice kernel that is removed during the milling process, which generates the familiar white rice. 

Rice bran is high in fat (around 20%), but is extremely unstable if not refined almost immediately, turning rancid quite quickly. Rice bran oil is the refined stabilised oil extracted from the rice bran.

What is gamma oryzanol?

Gamma oryzanol is a rice bran oil derivative with two major active molecules - sterol and ferulic acid. 

Trials in the United States, Japan and Australia have shown gamma oryzanol has positive effects on weight gain and performance, comparable to some anabolic steroids. 

Gamma oryzanol has effects on the body’s endocrine system, resulting in increased metabolism of fat and increased synthesis of protein, leading to increased lean body mass.

Research in horses showed the gamma oryzanol group had improved muscle to fat ratio, with better muscle definition in the rump, neck and over the withers. The horses supplemented with gamma oryzanol also maintained appetite better than the control group. 

In addition, studies have shown gamma oryzanol is a natural antioxidant and can lower cholesterol levels in the blood.

Gamma oryzanol has also been shown to reduce the risk of gastric ulcers and increased gastrointestinal motility caused by stress. 

The gamma oryzanol/ferulic acid molecule is a fat soluble material, which means that, like fat soluble vitamins A, D, E and K, fat is required for them to be efficiently metabolised in the horse’s digestive tract.

The benefits of antioxidants

At the molecular and cellular levels, antioxidants serve to deactivate certain particles called free radicals. Free radicals are the natural by-products of many oxidative metabolic processes within cells, which also takes place in humans. 

In horses, free radicals usually come in the form of O2 - the oxygen molecule.

If allowed to go their merry way, these free radicals can cause damage to cell walls, certain cell structures and genetic material within the cells. This is where antioxidants come into play. 

Antioxidants play an important role, ‘mopping up’ free radicals before they get a chance to do harm to the cell structure. 

Chemically, antioxidants work in several ways, including:

  • They donate electrons,
  • They donate hydrogen, and
  • They scavenge oxygen or they scavenge free radicals.

Antioxidants can be either synthetic (e.g. butylated hydroxyanisole - BHA) or natural products, such as vitamins A, C and E, which are also beneficial because they are essential nutrients.

Vitamin E is thought to be the most effective antioxidant, due to its plentifulness in the body. Rice bran oil is abundant with the main forms alpha, beta, gamma and delta tocopherol isomers, as well as the most active form of antioxidants, called tocotrienols.

Supplementation of antioxidants are especially important in performance horses as the level of antioxidant reserves in an un-supplemented horse can be quickly eroded when horses are exercising at high intensities.

Why add oils?

With the high calorie demands of elite performance horses, oils plays an important role in reducing grain intake. Oils contain 2.5 times more energy than oats and also are digested more efficiently in the horse’s small intestine. Thus, reducing the ‘sugar high’ sometimes associated with high grain intake.

Unless fat (e.g. some type of vegetable oil) is added to the diet, horse rations are very low in fat; typically less than 2%-3%. However, horses are able to digest and absorb dietary fat quite well (up to 20% of their energy intake). In fact, it’s important that diets contain at least some fat or oil as it is needed to facilitate absorption of the fat-soluble vitamins A, D, E, and K.

Omega essential fatty acids

The horse also needs small amounts of a linolenic, linoleic and oleic acids. These are special types of fatty acids, which are more commonly known as omega 3, 6 and 9 essential fatty acids.

Omega essential fatty acid have been shown to improve the health and structural integrity of cell membranes, reduce inflammatory responses from cells, laminitis and stomach ulceration, and improve coat and hair condition. As plant oils are high in unsaturated fats, they are often high in essential fatty acids, such as the omega group. 

What type of horses will benefit from being fed rice bran oil?

  • Elite performance horses
  • Endurance horses
  • Horses in show preparation
  • Yearlings prior to sales
  • Horses prone to tying up
  • Poor doers
  • Horse with stomach ulcers
  • Horses that can’t tolerate high grain diets
  • The advantages of feeding rice bran oil

Reducing the amount of grain in a horse’s diet and replacing the same amount of energy is quite beneficial to horses in several ways:

Less grain in a horse’s diet will reduce the caecal burden on the horse’s digestive tract. This will, in turn, reduce the amount of heat produced in the horse’s hindgut. For horses working in extreme temperatures, the addition of fat into a horse’s diet will reduce the amount of metabolic heat produced by the horses and, thus, enable the horse to cope better with the stresses of heat.

Recent research has showed that feeding fat over a period of time can be quite beneficial to horses as the body adapts to using fat more efficiently. This feeding practice has a sparing effect on muscle and liver glycogen levels. It is suggested this allows for more glycogen to be available at the closing stages of athletic performance, including racing.

There are also numerous other beneficial reasons to replace some grain with fat, such as greater feed efficiency of fat (80-90%), compared to unprocessed grain and most other forages (50-60%). 

Horses can only consume so much food per day. Adding oil reduces the amount of feed (weight) the horse has to consume in order to meet its energy requirements. When preparing horses for shows and sales, an addition of rice bran oil to the diet can also assist in body definition and coat condition.

Why rice bran oil and not rice bran?

For horses that suffer from high grain (starch) diets, nutritionists and veterinarians recommend the addition of fat to the horse’s diet as a replacement source of energy. Whilst rice bran is high in fat (18-20%), it also contains moderate levels of starch (20-30%). In contrast, rice bran oil contains no starch and the addition of this to the diet does not contribute to additional levels of starch in the diet.

HYGAIN RBO® Equine Performance Oil™ is a unique blend of pure rice bran oil, omega essential fatty acids and natural antioxidants. HYGAIN RBO® promotes growth and development of the muscular system, top line, and a healthy skin and coat. HYGAIN RBO® is included in many HYGAIN feeds, such as HYGAIN TRU GAIN®, HYGAIN® EQUINE SENIOR®, HYGAIN® SHOWTORQUE® and more.