Re: Feeding cracked corn versus corn oil

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

> Karen Webb kwebb@gssb.com
> Which method is better if you're trying to keep a horse in good condition
> without making him overly energetic?  I know corn is high in energy.
> There seems to be some debate over it causing problems with digestion by
> over-fermentation in the cecum.  However, I have also heard that corn oil
> inhibits Vitamin B(?) absorbtion.

OK,  the short answers first.  No, corn oil does not interfere with vitamin
B absorption.  Period.  There used to be some thought that fats interfered
with fat-soluble vitamin absorption, but in reasonable amounts, it really
doesn't do that either.  In fact, the body seems to get better at absorbing
fats (including fat soluble vitamins like A, D, E & K) when you feed fats.
Sort of the same idea as horses get better at trail riding if you spend alot
of time...well, trail riding.

As for the 'debate about corn causing over-fermentation in the cecum'.
Absolutely no debate about it, it's a basic physiological fact.  Now, this
is not limited strictly to corn, and it's a quantity-related thing.  Any
starch feed, including corn, oats, barley, milo, etc etc etc can cause
over-fermentation (a little more accurately referred to as cecal acidosis).
Here what happens.  When food leaves the stomach, it goes first into the
small intestine.  Enzymes break down simple carbohydrates like starch (and
other things like proteins and fats) and they're absorbed from the gut into
the bloodstream and/or lymph system.  If too much of either starch or fats
are fed, then they bypass the small intestine without having been
absorbed---the transport mechanism just gets overwhelmed.  So now the excess
starch moves downstream into the first part of the hindgut, which is the
cecum.  There are about 800 different species of bugs in the cecum, but a
certain proportion of them are the Lactobacillus species, which particularly
thrive on starch and other simple carbos.  When a big glut of it comes down
the pike, their population explodes and a much larger proportion of the
total population is occupied by these lactobacillus species.  One of the
things that they secrete as a by-product is lactic acid, which is used by
the horse as an energy source.  However, lactic acid also makes the pH of
the cecum more acidic, and that tends to kill off some of the other species
in there that are pH-sensitive.  In some cases, that just causes a little
extra gas, maybe some mild colic.  In extreme cases, the die-off releases
endotoxins which damage the lining of the intestine, causes a systemic
inflammation and can cause laminitis.  So there are some really good reasons
to avoid the cecal overload scenario.

As I said, it's quantity-dependent---most sources agree that more than about
4-5 pounds of grain at one time for a 1000-lb horse is probably going to
cause cecal acidosis to some extent, though its variable.  The starch
content of the grain also matters, and corn has the highest starch content
of any of the grains commonly fed to horses.  Particle size also makes a
difference, so the finer the corn is ground (with increased surface area),
the more of an effect its likely to have.

OK, I know what you were really asking is just whether you should feed corn
oil or corn, but the cecal acidosis thing is worth repeating every once and
awhile. :-)  Back to corn oil vs corn.

The deal between the two is that they both provide good energy and both have
their benefits and drawbacks.  Corn advantages- it's cheap, most horses love
it, it's high in energy and readily available and easy to feed.
Disadvantages, it has a limited amino acid profile (very deficient in
lysine), it's high in phosphorus (though lower than bran) and there's that
starch content thing.  Also, you mentioned the overly energetic thing---not
every horse gets silly on grain, but if yours is one that does, corn is
usually most likely to do it, because of the high starch content.

Advantages of corn oil - 2.2 times the energy as an equivalent amount of
corn, so much more calorie dense.  Doesn't provide any other nutrient other
than energy, so you can add it to a ration without having to worry about
messing up mineral profiles.  Has some metabolic benefits such as lowering
thermal temperatures, a handy thing in some hot climates, and tends to have
a glycogen-sparing effect if you feed enough of it for long enough.
Disadvantages, not every horse will eat alot of it, it can get pretty messy
and it has to be kept fresh or it loses nutrient quality pretty quickly.
Not the best thing to feed during a ride itself, as it slows gastric
emptying and my own preference is that other nutrients are in shorter supply
and greater demand.  Compared to other veggie oils, some horses prefer the
taste of corn oil, but corn oil doesn't have the anti-inflammatory
properties that some other oils do, which makes a difference if your horse
has some dermatology issues.

So my bottom line is that I don't really like feeding just one thing to a
horse.  I think you get a better balanced ration and avoidance of alot of
the disadvantages if you use a bit of this and a bit of that.  I happen to
like beet pulp alot because it has minimal disadvantages, it has great
feeding value (meaning alot of nutrition per gram) and some pretty nifty
metabolic advantages for distance horses, like increased hindgut fluid
retention.  I like mixed grains because the amino acid and mineral profile
is improved over using any one grain, and the cecal acidosis effect is
mediated somewhat.  I like a little added fat just because of the metabolic
benefits and the caloric density--you can get alot of calories into a horse
pretty quickly with a cup or two of fat.  I like just good old grass hay
because it's a necessity for gut motility and because of the psychological
benefits of having something in front of the horse all day.  And good
quality pasture is the closest thing to magic there is in horse nutrition.

So you get the idea of what's "best"---there's no one feed that's "best",
but the best ration is one that provides a balance of different nutrients,
that has minimal potential disadvantages, that's readily available in your
area with good quality and a decent price, that your horse likes and you're
willing/able to provide.  That might mean a commodity based ration or it
might mean a commercially mixed feed.  These days, even though I can balance
a commodity ration, I go the convenient route and feed mostly commercial
mixes---Omolene 300 to the young'un, Complete Advantage to the old folks
home, free choice grass hay and pasture all 'round, and Complete Advantage
plus a little tweaking here and there (a little more fat, a little extra
beet pulp, extra vitamin A & E, plus biotin) for the horse being conditioned
for endurance.  A big box of loose, white salt, I keep an eye on selenium
and I make a big damn deal out of making sure their water is sweet and clean
enough for me to drink if I wanted to.

This is probably far more than you wanted, but hope it helps. :-)

Good luck,
Susan G