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> The science I've read is European feedlot science--they've gone from using
> anabolic steroids to Clenbuterol to gamma oryzanol as the laws have changed
> over there. I'm not a bran fan for another reason: coats the gut and prevents
> absorption of some nutrients.
I'm not a bran fan either and about for the same reasons. I'd much
prefer feeding gamma oryzanol in a purified form for its anabolic
benefits than rice bran. See below for full-blown ranting.
> Anabolism takes place in response to stressors that must be overcome.
> Certainly these stressors are different from endurance animals to racehorses,
> but an endurance horse that starts losing flesh and appetite instead of
> coming on with exercise preparation is equally in need of nutritional
> support.
I'll agree with you there 100%. But I also agree with your own #1 rule:
"do no harm". If at all possible, I'd much rather provide nutritional
support for one system in a way that did not decrease integrity in
another system.
> When you have time, please write a short review of the phosphorus question.
> I'm relatively unaware here.
Short? Me? HA! See below.
I guarentee that I can provide just as much Mcal of energy with
> a better nutrient balance---lacking only the gamma oryzanol---for a
> whole lot less money than you can get by feeding rice bran.>>
>
> So can I, but gamma oryzanol is about the only worthwhile component in rice
> bran
Agreed, agreed, and agreed.
and it is gamma oryzanol that is producing the results that people
> notice and want to keep paying for.
So you'll be marketing purified gamma oryzanol soon, yes? :-)
OK, here's the deal on phosphorus. Tom, I know you already know 99% of
this, intuitively if not otherwise, forgive me for covering all the
bases for anyone else on the list that doesn't know.
As you know, alot of minerals have some sort of interactions with other
vitamins or minerals---copper and zinc, calcium and Vit. D, Vit E and
selenium. One of these interactions is between calcium and phosphorus.
The saying in animal science, who are a not-very-poetic and pathetically
easy to amuse bunch, is "As goes phosphorus, so goes calcium". What
they mean is that for every gram of phosphorus ingested in the diet, the
body must match that P gram with another gram of calcium before the
phosphorus can be absorbed through the intestinal wall. However, if the
required gram of calcium is not available from the diet, the phosphorus
remains the controlling factor and the body will STILL dig out that gram
of calcium from wherever it can---like from its storage depot in the
bones. It doesn't take a rocket scientist to figure out that in any
performance horse that's putting alot of stress on its bones, not to
mention remodeling bone in response to training, you do NOT want calcium
being pulled out and lowering the bone integrity.
This is where the whole idea of calcium-phosphorus ratios comes from.
The whole point is to make sure that for every gram of phosphorus you're
feeding, you're feeding AT LEAST an equal amount of calcium (a 1:1 ratio
or better), so that calcium isn't being continually mobilized from
bones. Most nutritionist advise that the ideal levels are somewhere
between 1.2-2 parts calcium to 1 part phosphorus, but the main thing is
just that more calcium is being fed than phosphorus.
The problem is that most grass hays contain only low to moderate levels
of both calcium and phosphorus, while the majority of cereal grains are
deficient in calcium and high in phosphorus. So in a horse being fed
alot of grain and grass hay as roughage, it would be very easy to have
an inverted ca-p ratio (less ca than p). A horse eating 14 pounds of
grass hay plus 4 pounds of barley/corn is going to have a ca-p ratio of
.96 to 1, which means that every day, 40 mgs of calcium is being removed
from the bones. OK, this isn't great but 40 mgs isn't all THAT much,
over an entire year about 15 grams of calcium. But still, if you're
going to pay all that attention to making sure every little detail is
just right in fine-tuning an athlete, making sure the bone integrity is
also anabolic instead of catabolic should be somewhere in the equation,
too.
Just to make another example, say the same horse is still eating 14
pounds of oat hay, but now he's getting six pounds of barley/corn. Now
his ca-p ratio is .86 to 1 and now he's catabolizing (losing) about 240
mgs a day, or about 88 grams a year. 88 grams is equivalent in weight
(not volume) to about a half cup of water.
I honestly don't mean to make this sound scary or melodramatic. Horses
have ALOT of calcium stored away, so it's not like an inverted ca-p
ratio is going to make their legs shatter next week. On the other hand,
catabolism is catabolism and it's just not that tough to fix an inverted
ca-p ratio.
So here's partially where rice bran starts to come in. Lots of people
see the nifty ads about rice bran containing 15-20% fat and so assume
this is a great thing to feed to horses. (Actually, fat content or not,
rice bran has less energy than wheat bran, corn, oats or barley, but
that's beside the point. Sorta.) So they go get a bag and feed it at
the recommended amounts, which is what? A pound or two? OK, fine.
What the pretty bag DOESN't tell you is that rice bran has a higher
phosphorus content than anything other feed, right around 1.57%. Wheat
bran is number two at 1.13% Add that to the above horse's ration and
now he's got a ca-p ratio of .55 to 1. That's 650 mgs a day being
pulled from bone, or 237 grams a year, equivalent in weight to more than
a cup of water. That's alot of calcium for a performance horse that has
better things to do with it. Granted, it's not all coming specifically
from the cannon bones, but still...from bone.
Not to scare the dickens out of anyone, but a few years ago when I was
hanging around the local equine hospital, a client brought in a lovely
imported warmblood breeding stallion for x-rays because he always seemed
to be progressively lame, even though he was only being ridden
dressage. They took the horse's history and radiographs, but on the way
back to his trailer, the stallion got frisky, got away from his handler
and went galloping merrily down the street. At the intersection, he
stumbled and went down and totally shattered a cannon bone and pastern
joint, which seemed a bit extreme under the circumstances---it wasn't
all THAT bad a crash. The damage was too great to fix and the very
valuable horse was put down. Later, after they developed the original
radiographs (now a moot point) the bones had so little calcium
deposition, they looked like something was wrong with the equipment's
contrast. It turns out the horse got colicky on alfalfa and was a hard
keeper to boot, so he'd been living for all his life on oat hay and ALOT
of grain and bran. However, this was a really extreme example, so don't
take this as the Voice of Doom predicting that everyone's legs will turn
to dust by nightfall.
OK, so much for inverted calcium-phosphorus ratios. Most everyone knows
that good-quality alfalfa is a dandy source of calcium, so all you have
to do to balance an inverted calcium-phosphorus ratio is add more
calcium in the form of alfalfa, right? Well, that's true. Adding five
pounds of alfalfa to the above ration will balance the ratio back to 1.2
to 1. Most people after hearing my patented Horrors of the Inverted
Ratios tend to want to REALLY make sure their ratios aren't inverted, so
that feed a pretty fair amount of alfalfa, 50/50 or better. After all,
the NRC even says that horses can tolerate calcium levels up to 7 to 1
without ill effect. This is one area where I will definitely agree with
you, Tom, that the NRC should definitely not be taken as the last word.
I read the study that the NRC based these conclusions on and the only
"ill effects" they were looking for were signs of toxicity, like you'd
see with wildly excessive selenium or sulfur. If the horses did not
actually drop down and froth at the mouth, NRC says that's good to go.
There is one syndrome of an inverted ca-p ratio (that is, too much
phosphorus, not enough calcium) that can be seen visually, called
miller's disease in the UK and bighead disease elsewhere. What happens
is that the calcium being removed from the bone is replaced by
connective tissue--an attempt by the body to create stability and
support when bone isn't available. Although it's going on throughout
the body, it will show up on the head, with an enlargement along the
jawbones, especially the upper mandible. It makes the whole face look
swollen and hence "bighead disease". However, this symptom may not show
up unless the inverted ratio is a severe one, and sometimes not even
then.
So here's the problem I have with rice bran and subsequently high
calcium levels. People feed rice bran for whatever reason---gamma
oryzanol, fat content, whatever. If they haven't heard about ca-p
ratios, the odds are higher that they might have an inverted ratio if
the primary source of hay is a grass hay. If they have heard about ca-p
ratios, then they predictably add a whole bunch of alfalfa to "balance"
the ratio back to where it's supposed to be.
However, just because the ratio is 1:1 or better doesn't mean minerals
are being fed at the optimum levels, and here's where we diverge a
little in racehorse management vs. endurance horse management. Let's
say you're feeding a horse 9 pounds of alfalfa, 5 pounds of oat hay, 2
pounds of rice bran and three pounds each of corn and barley. Lots and
lots of horses get this ration every day. The ca-p ratio is 1.72 to 1,
which most books, including NRC will tell you is within the ideal
range. Peachy. However, if you keep crunching the numbers, you'll find
out that you're providing approximately 61 grams of calcium, 36 grams of
phosphorus and 28 grams of magnesium (according to NRC data), which is
roughly four times as much calcium, 3.5 times as much phosphorus and 4.5
times as much magnesium as is actually required for maintenance. For
that matter, if the source of the alfalfa was California, then in
reality the magnesium content is probably considerably higher. Alfalfa
plants have the ability to concentrate magnesium and so when grown in
alkaline soil (like in California), the Mg content can be as much as
seven times higher than alfalfa grown elsewhere. (And NRC doesn't tell
you that either, by the way). So in California, the above ration is
probably providing more like around 80-90 grams of magnesium, about 13
times as much as is required.
So what, right? That's what kidneys are for. Well, here's the problem
and there are two biggies. One is the one that Tom pointed out, that
excessive phosphorus suppresses the absorption of other minerals. Yes,
it does, who knows how much. Frankly, as of the last 1989 edition, NRC
still didn't have a clue exactly what got suppressed and by how much,
they just know it does when fed to excess (like with rice bran). One of
the problems with excess calcium is that it tends to get the
calcium-mobilizing hormones lazy---there's always plenty of calcium
laying around, so no reason to have a high concentration of the hormones
that move it out of the bone and into the bloodstream. Calcium is used
as a regulatory factor in alot of physiological functions, not the least
of which is muscular contraction. An endurance horse that has used up
all his readily available plasma stores of calcium and can't mobilize
enough additional calcium from his bones (because the parathyroid
hormones got caught with their pants down) is going to go into an
electrolyte imbalance and potentially, thumps. (There are other factors
to thumps as well). Whether this would be a problem in racehorses as
well I couldn't say---maybe Tom knows.
On to the other problem. One of the leading causes of colic in horses
is enteroliths in the gut. The primary components that make up
enteroliths are nitrogen, phosphorus and magnesium. Nitrogen comes from
an excessive amount of protein, and nice, leafy alfalfa can be over 20%
crude protein. That same alfalfa, as demonstrated above, is also
contributing what can only be described as a sh**load of magnesium, and
if you're feeding grain and especially rice bran, guess where all that
phosphorus is coming from. If you're thinking this sounds like a recipe
on How to Grow Really Big Rocks in Your Horse's Gut, you're right, it
sure is. Here in So Cal, the majority of horses are still being fed
straight California alfalfa, the greener and leafier, the better. It
also just so happens that enteroliths are more common here than anywhere
else in the country, wonder why?
So here's the bottom line of why I am no fan of bran and specifically,
rice bran:
1) Other than gamma oryzanol, it doesn't provide anything that can't be
provided by other feeds better, cheaper and in better nutritional
balance. I'd still like to know if gamma oryzanol is available in a
purified form.
2) It's sky-high in phosphorus, which increases the possibility of an
inverted calcium-phosphorus ratio.
3) If the high phosphorus is "balanced" with alfalfa, then the high
nitrogen and magnesium content of the alfalfa is contributing to a more
alkaline condition in the hindgut and an increased chance of eventual
enterolith formation.
I am all for nutritionally supporting performance horses of any
discipline to keep them in an anabolic vs. catabolic state. Seems to me
that if you're going to go through all the trouble of conditioning the
buggers, giving them the raw materials they need to build appropriate
tissue is a fairly logical thing to do. But I also think that part of
smart management is providing nutritional support without compromising
any other part of the whole package. There are some supplements or
feeds with a few disadvantages that I would be willing to ignore if it
meant a big benefit in some area of performance. But, especially if
gamma oryzanol is available elsewhere, I don't think rice bran is worth
it in the long run.
Just my two cents, of course. Your mileage may vary.
Sorry to make this, as usual, into the Great American Novel. Hoped it
answered everyone's questions (and then some) about why I start foaming
at the mouth when people start talking about rice bran.
I need a margarita. Later.
Susan Evans Garlinghouse
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