mystery beet pulp weight gain (long)

[dave & abby bloxsom <cyclone@snet.net>]

So I'm entering this forum to present the results of my 3-rat
experiment; and to collect a set of possible explanations.

LAST WINTER, I had 3 idle adult horses of various breeds living together
in one paddock with a run-in shed. I fed 1/2 bale good Timothy/Orchard
grass hay per horse per day, split into 2 feedings.  I also fed a 10%
commercial sweet feed, 2 lg cans per feeding.  Feeding time was a
frenzy, and they wolfed everything down in a matter of hours.  The
horses held their weight all winter, although one was borderline & one
was fat.

THIS WINTER, I've divided them up.  One horse is in a new paddock (with
a new friend) with no shelter whatsoever (she's a Welsh Cob, never even
notices the weather unless it rains).  The other 2 are still in the
original paddock.  After following this winter's Ridecamp discussions,
I've revised my feeding plan a bit.  I'm still feeding the same amount
of the same quality hay - 20-25# per horse per day, but I throw a day's
worth out at (my) bedtime, once a day.  They're usually done with it in
about 20 hours.  They snooze, wander, and hoover crumbs for the next
couple hours.  At the other feeding, 16 hours or so after the hay (hay
still isn't finished), I give them soaked shredded beet pulp.  I'll
probably end up adding a vit/min supplement to that based on the results
of my hay analysis, but for the time being that's it - no oil, no
grain.  The dry volume of shredded beet pulp is actually about 75% of
the dry volume of grain I was feeding, and because beet pulp is lighter,
it's actually MUCH less by weight, dry.  All 3 are in excellent flesh,
neither fat nor thin.  Feeding time is easy, no rushing, no jamming
noses in the pails, no pushing, no fighting.

I presume the attitude changes relate to the fact that there's really no
"treat" involved - the Salad Phenomenon.  The big question is this - if
I'm feeding so much less feed by weight, and DE is actually WAY down
because the beet pulp is less energy dense than grain, why are they
doing so well?  Water supply/intake hasn't changed, and weather has been
equivalent.  Keep in mind one horse who used to have shelter is now
completely exposed to the elements.

Now I'm not complaining - don't get me wrong - I'm just wondering how
many different explanations for this can I collect?

Okay Ridecampers, go to it.

-Abby B