here's the rice bran article

[Susan Evans Garlinghouse <suendavid@worldnet.att.net>]

BMcCrary27@aol.com wrote:

> And why no rice bran?  I had always heard it was such a great product for
> adding weight to a horse.  Please educate me.
> 
> Thanks,
> Barbara

Barbara, here's the article on rice bran I mentioned.  Hope it answers
your questions.

Susan G


The Pros and Cons of Rice Bran
Susan Garlinghouse, MS
The Equine Research Center
California State Polytechnic University, Pomona


Maintaining weight in a hard-working horse can be a real challenge, and
trying to find the optimal, high-calorie ration is often confusing,
expensive, messy or a combination of all three.  In the past few years,
rice bran has become a popular feed both among show-goers desiring a
shiny coat, as well as among endurance and CTR competitors trying to
keep weight on throughout a busy season.

The primary attraction to rice bran, aside from its palatability and
convenience, is that it is marketed as being a source of fat---and rice
bran does indeed contain approximately 15-20% fat.  But does that alone
make it a superior feed?  It's not just the fat content which is
important in choosing appropriate feeds, but total calorie content. 
Even though rice bran contains more fat than any other commodity feed
except for flax seed or pure fat itself, the total energy (calorie)
content is less than any of the commonly fed grains, and not
substantially above the energy content of forages:

                        Energy                  Energy content
                        Content (Mcals/kg)     comparison to rice bran
Bermuda hay,
(29-42 days growth)      1.83                     69%
Alfalfa hay, early bloom 2.25                     85%
Beet pulp (dry)          2.37                     90%
Rice bran                2.64                    100%
Oat grain                2.97                    112%
Wheat bran               2.94                    114%
Barley grain             3.29                    125%
Corn grain               3.39                    128%
Vegetable oil            8.98                    340%


Therefore,even though a larger proportion of the calories in rice bran
are provided as fat, its total energy content is only slightly higher
than the forages alfalfa and beet pulp, and is less valuable than other
more traditional grains for providing energy.  Even good quality grass
hay, such as bermuda, provides pound for pound approximately two-thirds
as much energy as rice bran, and can be safely provided in much greater
quantities, thereby providing more total calories.  Although other
factors such as digestibility will also affect the total energy
available, a quick comparison shows that rice bran is not as dense a
source of calories as is often believed. 


The primary disadvantage, and the one most commonly overlooked by
horseowners, is the inverted calcium-phosphorus ratio.  Rice bran
contains 0.02% calcium and 1.50% phosphorus, one of the highest
phosphorus contents available from a non-mineral source.  

For example, a horse eating 18 pounds of bermuda hay is being provided
with approximately 25 grams of calcium and 16 grams of phosphorus, or a
ratio of 1.56 (1.56 grams of calcium for every 1 gram of
phosphorus)---very good. Equine nutritionists recommend an ideal
calcium-phosphorus ratio of between 1.2 - 2.  Any ratio less than 1 is
considered "inverted" and a serious imbalance in the equine ration. 
Although horses can tolerate ratios of up to 7 to 1, this would also be
excessive.  A discussion of the effects of excessive calcium in the
ration was covered last month in the article "Alfalfa for Distance
Horses---Too Much of a Good Thing."

Now add to this above ration five pounds of corn and the ratio drops to
1.18---just a touch below the recommended level, but still acceptable. 
But what if we add just two pounds of rice bran?  Now the ratio drops to
.74---inverted and not acceptable at all.  This means that for every day
that this ration is fed, approximately 260 mgs of calcium are pulled
removed from storage depots in the bone, or about 95 grams a year.  Over
the lifetime and career of the horse, this may contribute to a decrease
in bone density, as well as may decrease calcium availability for
muscular contraction during exercise.  In a young, growing horse, an
inverted ratio may also contribute to developmental orthopedic diseases.

To make things even more confusing, even though rice bran is extremely
high in phosphorus, it is at the same time, a poor source of phosphorus
itself.  What?  How can it be both?  Approximately 90% of the phosphorus
in rice bran is in the form of phytate, a naturally-occurring organic
molecule in which the phosphorus atom is bound by other atoms and
therefore is biologically unavailable to the horse.  In this form, the
phytate molecule still interferes with the absorption of calcium, but is
itself unavailable for absorption and utilization as a source of
phosphorus unless the phytate molecule is broken down by the enzyme
phytase.  Phytase occurs in relatively high levels in several grains
such as wheat and rye, but only in low levels in the grains (such as
corn) which are commonly utilized in equine rations.  Phytase is also
available commercially, but whether the additional expense of buying
another supplement offsets the disadvantages of the first supplement is
debateable.  Research conducted in the '80's on supplementation with the
yeast culture Yea-Sacc (which is currently added to several commercial
feed mixes) also indicated an increase in phosphorus absorption, though
the effects and mechanism are still not completely understood.  Although
the concepts of phytates and low bioavailability are not exclusive to
rice bran, they are important factors which should be considered when
formulating an equine ration.

Fine, you think---we won't feed rice bran every day, just before and
during a competition so the fat will help maintain energy.  In fact,
rice bran's fat content is a disadvantage during endurance-type
exercise.  Fat slows gastric emptying and therefore, the food
ingested at vet checks will not be digested and metabolized as quickly
as feeds with a low fat content.  Not only will the rice bran be slow
to leave the stomach, it will also slow the digestion of other grains,
electrolytes and roughages needed to maintain gut motility, energy and
fluid balance.  Furthermore, fats themselves are metabolized much more
slowly than are carbohydrate sources, such as grains.  Since from 50-70%
of rice bran's energy content is in the form of fat, very little energy
is going to be available to the horse during the competition directly
from the rice bran.  For these reasons, rice bran as well as other forms
of fat are not advisable during competition.

The final consideration is expense.  Except in rice-processing areas,
rice bran often costs more than $20 for a 40-pound bag.  Most horse
owners will gladly pay for premium feeds or supplements that deliver
optimum health and performance.  A careful cost analysis of rice bran
will generally demonstrate that equivalent or superior nutrition can be
provided by feeding other traditional, much less expensive feeds.

However, every cloud has a silver lining and even rice bran has some
good points.  It is an excellent source of vitamin E, superior to any
other traditional grain source.  On the other hand, relatively
inexpensive vitamin E supplements are available in any feed store for
less cost than an equivalent amount of rice bran-derived vitamin E.

Rice bran also contains the naturally-occurring substance gamma
oryzanol, which has been purported to have steroid-like properties and
help horses build muscle tissue.  Gamma oryzanol is also marketed in a
purified form under several brand names, and is particularly popular on
the racetrack to help Thoroughbred racehorses develop muscle tissue
quickly.  However, Heidi Smith, DVM, an endurance veterinarian and
equine practitioner in central Oregon, has observed that young horses 
fed gamma oryzanol either as rice bran or in the purified form, seem to
develop more stomach ulcers, and therefore, does not recommend rice bran
for horses under two for this reason alone.  Although no controlled
studies have been published, this possibility should be considered
before feeding gamma oryzanol supplements to young horses.

To summarize, here are the main points regarding rice bran:

1) Although marketed as a fat source, equivalent or more total calories
are provided by less expensive grains, including oats, barley and corn. 
Other feeds, such as beet pulp, provide fewer calories per pound, but
can safely be fed in larger quantities, thereby providing more total
nutrition.

2)  Rice bran is the highest non-mineral source of phosphorus among
feeds commonly fed to horses.  Depending on the forage source and other
fed concentrates, this may contribute to an inverted
calcium-phosphorus ratio and an imbalanced ration.

3)  Rice bran is high in phytate which, unless additionally supplemented
with phytase enzyme, impedes the absorption and utilization of both
calcium and phosphorus, possibly contributing to mineral deficiencies of
one or both.

4)  Fed during competition, rice bran's high fat content slows
gastric emptying, decreasing digestion and metabolism of other feeds to
maintain energy levels, fluid balance and gut motility.

5)  Rice bran is a good source of vitamin E, but equivalent and less
expensive sources are readily available in purified supplement form.

6)  Rice bran contains gamma oryzanol, which may have beneficial
muscle-building effects in some horses, but has also been possibly
associated with gastric ulcers in young horses.

7)  Rice bran is expensive in most parts of the country and is easily
replaced in the equine diet by other feeds which provide equal benefits
without the nutritional disadvantages.  Therefore, rice bran's only
inarguable benefit is its convenience and palatability.

Copyright Susan Evans Garlinghouse 1998.