Re: rice bran debate

["David M. Garlinghouse, Esq." <suendavid@worldnet.att.net>]

(For everyone else wondering who David Garlinghouse is---it's me, Susan
Garlinghouse, I'm just using my husband's laptop while mine is getting
yet more memory installed)...so let the games begin...

Hi Joe,

I'm glad you jumped into this discussion.  I really respect your opinion
and knowledge and have always enjoyed reading anything you've written. 
Since Dr. Reynolds from Natural Glo hasn't responded publicly yet (I'm
sure she will when she has a minute), I'm going to take the opportunity
to continue this discussion based on your comments, if that's okay with
you.  For the sake of everyone else on ridecamp, excuse me for including
some rather long passages from your original post.


> 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.

Yes, I sure did.  I checked for the DE content first in the NRC
reference, also from Equine Research's book Feeding to Win II---not a
reference text, but more recent than NRC, so wanted to see if there's
was something different (there wasn't, so I assume their numbers were
also from NRC); and finally from Lon Lewis' Equine Clinical Nutrition,
which is a pretty good reference text and more recent yet (1995). 
Lewis' value was slightly higher than NRC at 2.9 Mcal/kg, but still
considerably lower than the values you've gotten at KER.  I also checked
with a very recent text of food values in human nutrition, hoping their
numbers would be more recent, and those numbers were not anything close
to KER's numbers, either, though that rice bran is probably quite
different as well.


  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. 

Yes, I'll certainly agree with that---alot of the published values
aren't exactly cutting edge, but better values are often pretty hard to
come by.  I'm glad you've done some direct measurement.

 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?

Based on the numbers you've been able to derive, then I'll go along that
the processed rice brans are a good source of energy, and rank alot
higher on the list than where my numbers placed it; and I've always
conceded that rice bran is certainly easier to feed than corn oil, at
least for some horses (I, of course, have the weird ones that will slurp
up corn oil or FatPak straight, but won't touch rice bran).  

However, based only on energy values, and based on So Cal prices for oil
and rice bran, it still costs me twice as much to feed refined rice bran
as it does corn oil.  Someone else check out my numbers, but based on
the L.A. prices of $13 for 2.5 gallons of corn oil; and based on $24.50
for 40 lbs of processed rice bran (EquiJewel isn't available on the west
coast or at least I havent seen it---we have either Natural Glo or Satin
Finish), then raw rice bran costs me $0.51/Mcal; processed rice bran
based on KER's numbers cost 0.35/Mcal; and corn oil costs 0.17/Mcal.  So
I'll go along that rice bran is going to be more *convenient* Mcal for
Mcal, but even at the much higher DE numbers, corn oil is still going to
be more cost effective.  I don't think a pound or two is a big deal if
you're only feeding one or two horses, but it sure can add up if you
trying to feed quite a few and money is an issue, as I know it is for a
number of folks on this group.

> 
> 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.

Yes.  I don't know if you lurk on a regular basis, Joe, but in other
discussions on rice bran, when people like rice bran but are concerned
about the Ca:P, I've suggested they feed EquiJewel for that very
reason.  I'm hoping Judy Reynolds from Natural Glo will jump in on this
discussion---when I spoke to her on the phone last week, I asked why
they didn't do that as well, and she said their opinion was that the
problem was better solved for them by offering an extra Gro-Strong
supplement to be fed along with the Natural Glo.  Hopefully she'll find
a few moments to jump in and explain it better in her own words.


  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.

Well, this is where I got the information on phytates.  First was from
Lewis' Equine Clinical Nutrition---for the sake of everyone else here,
here's an excerpt from the relevant paragraph:

"Most phosphorus in cereal grains, oilseed meals and bran is in phytate,
a hexaphosphate ester of inositol, which in plants is present as the
calcium, magnesium and potassium salt.  For minerals bound to phytate,
as well as phytate phosphorus, to be absorbed and thus utilized, the
phytate must be broken down.  This is greatly enhanced by the phytase
enzyme, which is high in some feeds, such as wheat and rye, and low in
others, such as corn."

Okay, so we're in agreement about phytates, etc and the problem is that
the above paragraph doesn't specifically mention the phytase content in
rice bran, or even whether it's high or low.  So I went and asked Dr.
Mark Meskin at Cal Poly---he's a human nutritionist, but his specialty
is mineral metabolism so while utilization is different between species,
he's still a pretty good source on mineral content of some foods. 
Anyway, he thought rice bran was pretty low in phytase and that it would
have to be supplemented exogenously to make the phosphorus content
bioavailable, hence my statements in the article.

I try to keep up with the journals, but if you have some references on
the phosphorus availability, would you mind sending them to me privately
when you have a minute (or just the journal and general date is fine)?
I especially like to keep up on this sort of thing, and I'd like to put
this into my files.

A large part of why I get a little nervous about rice bran for distance
horses is because endurance people for the most part don't feed alot of
alfalfa, so the Ca:P is more of an issue than it might be for other
disciplines and production levels.  I haven't seen a bag of EquiJewel,
and I know KER puts alot of effort into public education through your
articles, website, etc, but this same level of information isn't
necessarily true for every brand of rice bran out there.  The last time
I looked at a bag locally (which granted, was about a year ago) there
was nothing that warned the consumer about overfeeding rice bran---they
DO recommend feeding just a pound or two (which is fine by me in most
cases) and some brands like Natural Glo also advise supplementing with
an extra mineral supplement.  But, the problem I have with that is that
people WILL feed based on "More is Better" (I know of a number of people
that feed well in excess of two pounds a day, some up to 6-7 lbs) and
very few also feed the mineral supplement, because they figure it's
optional.  Those are the people that I think are inadvertently going to
get into trouble with rice bran and if the basic flaws in rice bran's
mineral profile aren't going to be fixed as EquiJewel has been, then I
think ALOT more effort needs to be put into public education regarding
the intelligent useage of rice bran.  Just my opinion, of course.

> 
> 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.

Yes, Steve Duren and I had a nice conversation about some of your
upcoming projects while at ICEEP 5.  They really sounded neat, and
especially relevant for practical application in endurance
horses---still not enough of THAT around.  Anyway, not to doubt you at
all (since you're far more qualified than I am) but personally, I'm
still a little uncomfortable about slow gastric emptying during an
endurance ride.  I agree that grains passing into the cecum undigested
aren't ideal for a variety of reasons, but I wonder if that is still
going to be the case when grains are fed in small, frequent meals as
opposed to larger, bolus meals?  When somebody happens to ask, what I
generally recommend is dividing up several pounds of grain into baggies
and rather than only having it available at vet gates, handing it out a
mouthful here and a mouthful there every half hour to an hour along the
trail.  It seems that doing so is going to not only result in more
consistent absorption and a steadier glycemic response, but also is
going to help out maintaining fluid balance by avoiding episodic meals. 
With a little practice, it's easy to do without even getting out of the
saddle and the reports coming in from the field are that energy and
performance is improved over the episodic feeding.

So, if a horse is fed this way throughout the ride, as opposed to only
at the vet checks, would you still prefer a slower gastric emptying
rate?  I would kind of think a small, steady source of carbos throughout
might best be moved on through the stomach and on into the small
intestine.  What do you think?

Also, is it your opinion that fats (from any source) is going to be a
better source of energy than carbohydrates actually during a ride?  My
understanding has been that while over-reliance on carbohydrates is
going to decrease FA utilization---not good during endurance exercise,
though Tom Ivers and I have been wrangling about this for years
now---some supplementation of glucose during the event itself is
beneficial to avoid glycogen depletion.  Based on this aspect alone, I
prefer a mixed grain source (in addition to tons of hay, of course)
rather than fats actually during the ride itself.  What are your
thoughts?

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

Joe, I really look forward to hearing your additional thoughts, this is
big fun (which if nothing else, indicates that I really need to get out
more).  I'm planning on editing the rice bran article accordingly to
reflect the differences between raw rice bran and some of the better
bran products---as you say, this is how we all learn.

Hope you have a few minutes to say hi next June at ENPS.

Susan Garlinghouse