Rice bran is the outer brown layer of the rice kernel. Rice bran is a rich source of fat (rice oil), several B vitamins, and phosphorus. Most laboratories estimate the fat content of raw rice bran at between 20 and 25%.
To prevent rice bran from becoming rancid because of its fat content, it must undergo a process that stabilizes the rice bran through heat and pressure. This process inactivates the lipase enzyme that leads to rancidity, without destroying the nutritional value of the rice bran.
Stabilized rice bran is defined by the American Feed Control Officials' publication as rice bran which has been treated soon after milling by heat or other means that will substantially reduce the lipase activity. As proof of stabilization, the government regulates that free fatty acid content for stabilized rice bran will not exceed 4%.
Research has confirmed that the fat in stabilized rice bran is highly digestible and is equally as digestible as corn oil. Stabilized rice bran is a good source of B vitamins including thiamin, niacin and riboflavin. These B vitamins function in many chemical reactions which generate energy for the body.
In addition, fat in rice bran contains gamma oryzanol which has been suggested to have muscle building properties in horses. While this has not been proven scientifically, a number of reports from the field have indicated that young growing horses, hard keepers, and equine athletes have shown improved body condition after rice bran supplementation.
Horses that may benefit from rice bran
Many types of horses can benefit from the addition of fat in the form of stabilized rice bran. According to Kentucky Equine Research, performance horses benefit primarily in two ways. First, the dietary fat in rice bran serves as a calorie-rich feed stuff which helps the athletic horse meet its energy requirements.
Second, for performance horses that have trouble maintaining their weight, stabilized rice bran functions as an additional energy source that does not require feeding more grain in the diet.
Rice bran also has a significant amount of fiber in addition to the fat. The fiber in the rice bran makes it less likely to cause digestive upset than other calorie sources that contain large amounts of starch.
Rice bran feeding caution
A potential problem with rice bran is that some rice brans contain more phosphorus than calcium. This may create an imbalance in rations that use grass hay as their primary forage source. Therefore, it is important to make sure the horse is getting a balanced diet.
Stabilized rice bran is a safe, palatable means of adding calories to the diets of many types of horses. Because many of the calories originate from fat, adding stabilized rice bran to the diet avoids potential digestive upset which may occur with high carbohydrate grain feeding.
Rice bran also provides fatty acids essential for healthy skin and hair. To achieve superior coat condition, heat-stabilized rice bran can be a supplement given to horses of all ages.
Rice bran and metabolic diseases
According to the University of Minnesota Equine Center, replacing carbohydrate calories with rice bran and its useful fat is helpful for quarter horses and draft breeds that are especially susceptible to polysaccharide storage myopathy which is characterized by the "abnormal accumulation of the normal form of sugar stored in muscle (glycogen) as well as an abnormal form of sugar (polysaccharide) in muscle tissue.”
Carbohydrates appear to worsen polysaccharide storage myopathy and by replacing carbohydrate calories with s form of fat such as rice bran, improved up to half of affected horses.
Should you feed rice bran - reasons why
Five of the top reasons that horse owners and managers offer stabilized rice bran according to Kentucky Equine Research Staff:
- Putting or keeping weight on horses (e.g., hard keepers, horses involved in heavy exercise);
- Altering the diet of horses with PSSM and endocrine disorders, such as Cushing’s disease and metabolic syndrome (because replacing starch with fat as an energy source is advocated by nutrition experts);
- Managing gastric ulcers;
- Providing a fat source to optimize coat health; and
- Helping modify some behavioral concerns (fat provides a cool, slow-release energy).
Pelleted, meal, powder, or extruded: Which will work best for your horse?
Stabilized rice bran weighs in at approximately 1200 calories per pound, making it a very effective weight building feed. Which form you choose to feed, pellets, meal, or extruded, depends largely on your own preferences and what is available in your area. As owners of picky horses know, it also depends on your horse's preferences.
Rice bran meal and pellets have been available for some time through a number of horse feed suppliers. More recently, equine feed companies have developed methods of extruding rice bran into stabilized nugget form for easier feeding to horses. These extruded rice bran nuggets for horses are similar in appearance and texture to extruded cereals for humans such as Cheerios and Rice Krispies and the extruded nuggets now popular in dog food.
Extrusion cooking has proved to be the most effective process in stabilizing rice bran by inactivating the lipase, destroying the bacteria and stabilizing the free acid and so reducing the rancidity and increasing the storage life.
The extrusion process destroys the enzyme immediately after milling and therefore stabilizes the oil content and preserves the nutritional value of the rice bran. The increase in free fatty acid level of extruded rice bran is significantly lower than that of raw or pelleted rice bran during storage.
Also anti-nutritional factors such as trypsin inhibitors are destroyed by extrusion cooking. This provides a high-quality product that needs no chemical preservatives and has a one-year shelf life.
Along with improved shelf life, the formulation of additional varieties of extruded rice bran combinations with additional vitamins and other ingredients such as flax seed has lead to extruded nuggets that meet nutritional needs of different types of horses depending on physical and work needs.
Great overview article of the technical aspects of extruding rice bran: Stabilizing Rice Bran through High Shear Extrusion