rice bran debate

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From: Dr. Joe D. Pagan 
Email: pagan@ker.com

Dear Ridecamp subscribers

My name is Dr. Joe D. Pagan and I am the president of Kentucky Equine Research located in Versailles, Kentucky.  Kentucky Equine Research (KER)  is an equine nutrition research, consultation and product development company that works with companies around the world to develop products for specific equine applications.  We were the official supplier of feed to the 1996 Olympics and have developed a number of products for endurance horses, including the electrolyte Endra-Max, endurance feeds for Pennfield Feeds in the east,  LMF feeds in the west, and a stabilized rice bran called EquiJewel.  I recently attended the World Endurance Championships in Dubai where we supplied feed and supplements for several International riders including Valerie Kanavy.  Other nutritionists on my staff include Dr. Steve Duren in Idaho and Dr. Kathleen Crandell in Virginia.

KER operates a research facility in Kentucky where we conduct a great deal of research in equine nutrition and exercise physiology.  This facility includes a high-speed treadmill which we use to test various feeds and supplements.  One product that we have extensively studied is rice bran, specifically EquiJewel from Producers Rice Mill in Stuttgart, Arkansas.  I have read with interest the exchange about rice bran on your bulletin board and would like to add a few bits of information that may help clear up some of the confusion.

Susan Garlinghouse posted an article entitled "The Pros and Cons of Rice Bran" on Tuesday, January 12.  The article was very well written and contained a great deal of useful information, but unfortunately, some of the information pertaining to rice bran was not completely correct.  I would like to share some data that we have gathered that contradicts some of the key points made by Susan.  I apologize for not making these results available sooner, but getting scientific research into the hands of horse owners is often difficult to do.  If you are interested in nutrition, then I would suggest our web site (ker.com) where we have a large archive of free information in our library section and where we also post our Quarterly magazine EquiNews.

Now for the data:
A key (and valid) argument made by Susan about choosing an appropriate feed is its total caloric content.  Susan relied on information published by the 1989 NRC about the energy density of rice bran when she made her case against rice bran.  I'm afraid that the value used by the NRC is much lower than is true.  Charlie Thomson suggested that this number was low because the NRC tested raw rice bran, but the answer is even simpler than that.  Many (maybe most)  energy densities listed in the NRC have not actually been measured in horses.  Many have been taken from other species (cows and pigs) and some have been calculated using regression equations.  Anyway, we have directly measured the digestible energy (DE) content of both 15% fat and 20% fat rice bran.  Susan cited a value of 2.64 Mcal/kg for rice bran.  This is the value that the NRC assigns to a 13.6% fat rice bran.  As I'm sure you know, the higher the fat the higher the DE content and most rice brans have closer to 20% fat.  The measured DE content of a 15% fat rice bran in our lab was 3.17 Mcal/kg and the DE of EquiJewel (20% fat) was 3.78 Mcal/kg.  This is 143% higher than the value used by Susan and would rank it only below pure vegetable oil in her list of common horse feed ingredients.  It is also interesting to note that 1 lb. of EquiJewel provides the same number of calories as 1 cup (8 fluid ounces) of corn oil.  Which is easier to feed?

Susan also correctly pointed out that many rice brans have a badly inverted calcium:phosphorus ratio, but as was already stated on this bulletin board, we corrected that imbalance in EquiJewel.  Susan also mentioned that the phosphorus in rice bran was not digestible.  This is actually not the case.  The phosphorus in rice bran (and wheat bran) is very digestible and we have a lot of data to prove it.  This is because even though a great deal of the phosphorus occurs as phytate, bran contains a large amount phytase enzyme which breaks phytin phosphorus down.  Of course, this is not such a good thing if the ration has more phosphorus than calcium, but when balanced, rice bran can be a good source of phosphorus for horses.

Susan also suggested that rice bran (or fat in general) should be avoided in a vet gate meal because it delays gastric emptying.  I agree that gastric emptying may be delayed (much of the research that makes that argument comes from my lab), but I don't think that is such a bad thing during an endurance ride.  We have shown that exercise increases rate of passage through the digestive tract and this may lead to undigested grain entering the large intestine.  This could lead to a number of problems including colic and founder.  We are currently conducting research with Arabs regarding feeding during a vet gate and  hopefully I will have those results to you this spring.

I hope that these comments are helpful and keep up those lively discussions since that's how we all really learn.

Sincerely,

Joe D. Pagan, Ph.D.
President
Kentucky Equine Research