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I'm going to pool responses to everyone's comments and first off, agree with
everyone.  :-)  Yes, alfalfa can contribute to DOD (developmental orthopedic
disease); yes, mineral supplements affect DOD and yes, it (sort of) all
comes down to carbohydrates.

There's a pretty substantial amount of research demonstrating what
contributes the most to DOD in young, growing horses is being fat.  For most
horses, the source of calories is grain, but can also be just as damaging if
the excess calories come from added fat, too much protein, whatever.
Regardless of the source of calories, any energy in excess of the foal's
growth requirements are sent towards increasing body mass---the halter horse
breeder's dream of weighing a thousand pounds at a year of age and jiggling
when they trot into the ring.  The problem is that bone growth doesn't
increase at the same rate as body mass, either because minerals weren't fed
at the appropriate amounts or ratios, or because developmental cartilage
can't ossify into mature bone quickly enough to keep up with body mass.

Okay, so a quick side trip into how bone is supposed to normally develop.
In a young, growing animal, collagen develops most rapidly along the long
axis of the bones, for example, the cannon bones.  These areas are called
the epiphysis or epiphyseal plates.  Enzymes called lysyl oxidase allow the
collagen to cross-link, minerals (mostly calcium, phosphorus and some
magnesium) precipitate and ossify and mature bone is formed.

If anything occurs to disrupt this ossification process, then you get
abnormal bone development, and there are *lots* of things that can
potentially go wrong in this area besides a nutrition problem.  Trauma can
physically disrupt the epiphysis, causing what's called a Salter-Harris
fracture; conformation problems can cause abnormal biomechanical forces on
one side more than another...you get the idea.  However, the most prevalent
cause of problems appears to be nutritionally based, in combination with
excess rate of growth and excess body mass.

As commented on above, a lot of young horses are fed to produce rapid
growth, often without paying strict attention to the mineral profile.  If,
for example, a copper deficiency exists, then the enzymatic cross-linking of
collagen  is impaired and you get a "soft bone syndrome" which can persist
into adulthood.  Excess zinc causes the same thing, not directly, but
because excess zinc suppresses copper absorption and metabolism.  Incorrect
calcium-phosphorus ratios and amounts are another cause, though less well
clinically defined.  So the common thread here is that babies that are
growing too fast aren't giving their bodies sufficient time to lay down
quality bone; and the problem is exacerbated by rations that aren't
excruciatingly anal-retentive in providing the proper mineral profile.

How does alfalfa contribute to all of this---well, for starters, the alfalfa
is usually between 16-20% crude protein, often higher because we gotta give
those babies dairy-quality, glow-in-the-dark, fifth-cutting alfalfa that
tests out at 25% protein, dontcha know.  Not only is it a source of excess
protein, which is then utilized as an energy source, but its high
digestibility also contributes to excess calories.  Last of all, the high
calcium content, relatively low phosphorus and variable copper *can*
contribute to mineral problems if not balanced correctly with other feeds.

So, as I've been foaming at the mouth about for years now <g>, alfalfa in
and of itself is not a monster---only when it's fed inappropriately.  And
straight alfalfa for babies between six weeks and two years old is
absolutely inappropriate.  There was a study published a few years ago where
youngsters were studied for quality of bone growth, and where the only
difference in diet was the amount of alfalfa fed.  In the group where
alfalfa was less than a third of the hay ration, there was minimal incidence
of DOD problems.  In the group fed alfalfa free-choice, bone problems
galore.  Pretty strong evidence if you ask me.

So, the take home information here is that excess calories from any
source---carbohydrates, fat or protein---all contribute to too-rapid
increase in body mass over bone growth.  Incorrect mineral ratios and
amounts---either from home-mixed commodity rations, excess alfalfa, or
feeding babies supplements formulated for adults---contributes to the
problem.  Add on top of that excess trauma from forced exercise at a young
age, conformation problems, genetics and a continued pressure to produce
youngsters in the show ring that look like adults and bingo, you've got DOD
that affects the quality of the bones for life, including after the
youngster has been sold as a performance prospect.

One more myth to lay to rest here is that you'll get a bigger adult if you
super-feed them as babies.  No, you don't.  If you have a foal genetically
programmed to grow to 15.2, then assuming he's not outright starved into
being stunted (and that's actually pretty hard to do), then that horse is
going to grow to be 15.2.  Overfeeding the baby won't make him 16
hands---it'll just get him to 15.2 at a year old instead of two or three or
four.  And will also likely make him crippled to boot.

If any one ever wonders why I jump up and down about feeding a commercially
formulated foal pellet to broodmares and foals and not trying to mix your
own ration at home, all of this mineral business is why.  It's just too easy
to get the minerals messed up, and even if you don't get outright
epiphysitis (actually a misnomer, epiphyseal dystrophy is more correct) or
OCD, you're still not getting the quality of bone growth that you could be.

So here are the general guidelines for feeding babies for quality bone
growth (notice I didn't say quantity, I said quality)<insert sound of
cracking whip here><g>:

1) Start your pregnant broodmares on a top-quality broodmare-foal pellets in
her third trimester.  She'll need the calories during lactation regardless,
but the higher minerals in the pellets will help avoid nutritionally-based
angular limb deformaties in the developing foal and give her better mineral
stores that (variably) are passed along to the foal during lactation.  While
you're at it, supplement her with an extra 1000-2000 iu vitamin E per day as
well---she'll have better IgG levels in the colostrum when she foals.
2)  It's okay (though not necessary) to feed straight, leafy alfalfa to the
mare during late pregnancy and for the first 6-8 weeks of lactation once the
foal is on the ground (obviously, switch the mare over gradually, not
overnight).  She'll benefit from a little extra calories, protein and
calcium and the softer hay will be easier for kiddo to start messing around
with.  Around 6-8 weeks, start adding in some top-quality grass hay, so that
the alfalfa constitutes 25% or less of the hay ration by the time the foal
is 16 weeks.  By this time, the foal should also be getting a share of Mom's
foal pellets.

3)  Let's assume the foal is weaned around 5-6 months.  At this time, he
should be getting free choice grass hay or pasture, if he's getting any
alfalfa at all, it should be limited to less than a half pound per 100
pounds of expected mature body weight.  For example, if you think Junior
will mature to be 1000 pounds, then don't feed more than 5 pounds of alfalfa
per day between 6-12 months of age.  There are some published
recommendations that say after a year of age, it's okay to feed alfalfa free
choice.  I don't agree with that, I think the half pound of alfalfa per 100
pounds of mature body weight is a good rule of thumb regardless of
age,(unless the horse is a lactating broodmare as discussed above).

4)  Just to thoroughly beat this point to death, alfalfa is NOT essential
for any horse.

5)  Never, never, never, never feed weanlings creep feed grain free choice.
I don't care how big and frisky those babies looking romping around in
pasture, you're not doing them any favors giving them free access to grain.
The general rule of thumb for feeding grain (and by grain, I mean a mix
formulated specifically for foals) is:

a) Nursing foals (age 0-4 months) - maximum 0.5 - 0.75 lbs/100 lbs of
present body weight
b) Weanlings - (age 4-12 months) - maximum 1.7 - 2.0 lbs/100 lbs of present
BW
c) Yearlings (12-18 months) - maximum 1.3 - 1.7 lbs/100 lbs of present BW
d) Long yearlings (18-24 months) - 1.0 - 1.25 lbs of present BW
e) Two-year-olds (24-36 months) 1.0-1.25 lbs/100 lbs of present BW
NEVER feed more than 0.9 lbs of grain per 100 lbs of expected mature body
weight (this takes precedence over above recommendations). Never feed more
than four or five pounds of concentrates per meal, and never feed
concentrates before hay.

Example: You have a 16 month old yearling that weighs 800 lbs, that you
expect will mature at 1100 lbs.  Based on 1.3 - 1.7 lbs of grain/100lbs of
BW, you should be feeding 10.4 - 13.6 lbs of grain per day.  However, based
on a mature body weight of 1100 pounds, this horse should be fed no more
than 9.9 lbs of grain (11 x .9 = 9.9), split into at least two meals.

Do NOT try mixing your own grain mix for babies.  You won't get it right and
it's not worth NOT getting it right.  Find a good commercial mix formulated
for broodmares and foals and don't believe the salesperson that tells you,
"Oh, the performance horse mix is good for foals, too".  It's not.  You want
a mix where the crude protein is around 16% and the protein source is
derived from soybean meal; with a copper content of 55-60 ppm; and zinc
content of around 200-220 ppm.

If you're feeding a "complete" foal ration, like Equine Junior or something
similar, then the crude protein should be around 14%; copper should be
around 50 ppm and zinc around 175 ppm.  The above guidelines on how many
pounds per day don't apply to the complete rations, just to concentrate
mixes.  For the complete rations, follow the directions on the bag (and I
strongly recommend one of the name brands, like Purina, Nutrena, Buckeye,
Pennfield, Triple Crown, etc) and just adjust to the right semi-lean body
condition.

Don't feed babies added fat.  You're adding extra calories without
accompanying minerals and more likely to contribute to too-rapid increases
in body mass without increases in bone mass.

Last but not least, never feed any baby so much that he's fat, or even
chubby.  Babies put on body fat differently than adults do, but at any age,
you should be able to easily feel ribs with the flat of your hand, and maybe
just barely see them as well.  No gutters along the topline, no jiggling
when they trot.  If in doubt, have a halter breeder come over to take a
look---if they shriek in horror and insist you put another 50-100 pounds on
that baby right away, then he's probably just right where he is right now.
<g>

Hope this helps. :-)))

Susan G



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