Re: RC: Re: Feeding During an Endurance Ride

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

>
> How does lysine affect protein requirements/usage?  What effect would
there be
> from feeding a ration deficient in lysine but otherwise with more than
necessary
> protein?  Would not having enough lysine mean that not all of the protein
is
> metobalized?  (Can you tell yet that I have no idea how metabolism works?)
>
> -Tamara


Lysine is one of the essential amino acids---"essential" meaning that the
animal cannot synthesize lysine from other substrates, it has to be directly
supplied in the diet.  Lysine is considered the "first limiting amino acid",
in that it's the aa most likely to be deficient in most animal
diets---unless you're feeding some exotic and wildly synthetic lab ration
(which is unlikely), if your ration is sufficient in lysine, then it is
almost certainly going to contain sufficient amounts of the other essential
amino acids.  And no, if you're deficient in lysine, enough total protein is
not good enough---it has to have enough lysine, specifically.

Here's what happens if you don't have enough of any essential amino acid in
the diet, and excuse the Romper Room explanation.  Amino acids are called
the building blocks of protein---a string of amino acids is synthesized,
attached to other strings of amino acids, eventually it's folded and bent
and tucked together until it makes a protein molecule---which along with
other types of molecules, may eventually build a red blood cell, a membrane,
an enzyme that regulates metabolism, a cellular component that produces
energy---whatever.  There are thousands and thousands of different types of
proteins within the body, all with specific functions.

Ok---so the blueprint for each of these different types of tissue proteins
are all contained in the DNA.  When the body is triggered to manufacture a
protein, it starts putting together the amino acids in a very specific
sequence---if the sequence is wrong, you have all kinds of trouble, so the
pattern can't be changed.  Let's say that you're building an sequence of
amino acids, and the eighty-fourth amino acid is lysine.  The ration is
deficient and there's no lysine available, and the body can't manufacture it
or get it anywhere else.  It *cannot* substitute another amino acid, so if
there's no lysine available---well, the whole strand is dissolved and that
protein just doesn't get made, regardless of how badly the body might need
it.  It may not be a big deal, or it might be a very big deal---it all
depends on how important that protein was.

So, yes, it's important that the ration contain not just enough protein as a
whole, but specifically, enough of the right kinds of protein.  So if your
ration is deficient in lysine, it's also possibly deficient in other
essential amino acids---and that alone might explain some of Roo's weight
problems if that's true in your case.

Hope this explains it for you.

Susan Garlinghouse