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> I am reading 1993 Trail Blazers and their series of equine
> nutrition..it is most helpful and slowly, but surely, I think I'm
> starting to absorb this stuff! Thanks Linda Romander for letting me
> borrow them. I wish the libraries had them too...
You might check with some of the university libraries, especially those
with Animal Science departments. Alot of them carry TB.
>
> Oat Hay. Oats are listed as up to 50% starch. Does that include oat
> hay which I thought would be fiber mostly?
Whole oats, oat groats, oat hay and oat straw all have different
nutritional values. Oat groats have the highest soluble carbohydrates
(energy) and lowest fiber, oat straw the lowest energy and highest
fiber, although even straw isn't entirely fiber. Fiber for horses is a
somewhat different concept than fiber for people, only because horse can
derive nutrition from fiber where humans can't. When people eat fiber
(bran, veggies, Metamucil, whatever), the majority of the fiber will
pass through the digestive system undigested, thereby providing the bulk
that we want it for in the first place. This is because humans lack the
enzymes and microflora necessary to break down the chemical bonds that
hold the polysaccharide chains together.
Well, horses don't have the right enzymes either, but because they
do have a cecum, and the associated microflora in it, they are able to
break down the fiber in feeds to a certain extent and derive energy from
it through microbial fermentation. Depending on the feed, the amounts
and types of carbohydrates in a feed will differ. Feeds like corn will
contain high amounts of soluble carbohydrates and relatively little
structural carbohydrates (less than 10%). Forage feeds, such as oat
hay, will contain a lot less soluble carbohydrates and (with plant
maturity) an increasing amount of structural carbohydrates tied up in
the plant cell wall. Some of these structural carbohydrates, like
cellulose and hemicellulose can be utilized somewhat by horses. Some of
the cell wall content, like lignin, cannot be utilized at all and just
provides bulk just as it does in humans.
If you have a chance to take a look at feed analysis tables (like the
ones in the NRC's Nutrient Requirements of Horses)(which costs about $20
and is very handy to have around), you'll see listed fiber %, NDF % and
ADF %. The fiber % is the amount in the feed which is undigestible by
the horse and doesn't do anything other than provide bulk. NDF stands
for Neutral Detergent Fiber (which just refers to the method used to
analyze it) and is the amount of complex carbohydrates contained in the
plant cell walls whether it's digestible or not. The ADF % is the
Acid-Detergent Fiber, which is the same thing as NDF except with the
hemicellulose removed.
SO...as an example, oat hay has fiber, NDF and ADF % of 29.1, 57.1 and
34.8%, respectively. OK, big deal. This is how you get the useful
information. Take the NDF % and subtract the ADF % (57.1 - 34.8 =
22.3%) This means that of the total 57.1% fiber, 22.3% of it is in the
form of hemicellulose, which is at least partially utilized by the horse
for energy production. Then take the ADF % and subtract the fiber %
(34.8 - 29.1 = 5.7%) This is how much cellulose there is, also somewhat
utilized. If you add together 22.3% and 5.7%, you'll get 28%. This
means that out of 57.1% total fiber, 28% of that fiber is at least
somewhat useful in energy production. This is in addition to the
easily-digested energy provided as well by fat content (yes, even hay
has some fat to it) and through soluble carbohydrates.
Regarding alfalfa...they
> say don't feed accessive protein. Some indicated to me privately I
> should feed none. So, I'm a little confused....(as usual). Comments
> are appreciated.
For the most part, you shouldn't feed too much protein, for a variety of
reasons that have been pretty well discussed elsewhere. I'm a real
killer against feeding horses straight alfalfa in most cases, but that
doesn't make alfalfa the Root of All Evil. It's a very good feed and a
terrific source of lysine (the amino acid in shortest supply), calcium
and lots of vitamins and minerals. It's just a matter of not providing
too much of a good thing. For the most part (and I know I'm
generalizing here), if you feed less than 50% of your hay ration as
alfalfa, along with a good grass hay as the other 50%, you're not
providing too much. Personally, I feed my own horses closer to 25%
alfalfa and 75% bermuda, plus grain when they need it.
There are alot of people who don't feed any alfalfa at all, and their
horses do just fine. But, like anything else, you have to be careful
about "absolute" statements about Not Ever Feeding Alfalfa---I compare
this to the statements "Never let a horse drink water while he's hot",
which obviously we do all the time in endurance, happily avoiding alot
of dead horses that way. It's all in understanding how to use your
resources intelligently, instead of following absolute rules.
For example, if you feed your horses bermuda hay and a small to moderate
amount of grain, maybe some corn oil added, then you probably don't need
alfalfa. However, if you feed alot of oat hay (which has a higher
phosphorus content), plus a large amount of grain (also high in
phosphorus), plus, say, a nice big bran mash (really really high in
phosphorus), then I would say you should definitely replace some of the
hay ration with alfalfa to help balance out the calcium-phosphorus
ratios.
Basically, feeding alfalfa is like feeding anything. The more knowledge
you have, the better-informed a decision you can make, rather than
worrying about Absolutes.
As usual, I got too long-winded. Hope this helps some.
Susan Evans
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