Ridecamp: Re: [RC] B.C.A.A. Complex--Long answer: Amino Acids 101

I don't know how Susan feels, but "marketing ploy" comes to mind (funny how
suspicious I get about that, ain't it?).  Here's why. There is no question
that protein quality is as important if not more important than quantity.
Ever since I learned about proximate analysis, and the fact that the reason
those values have been used on feed tags is because of heavy lobbying by the
feed industry (the tests in proximate analysis are relatively cheap to
perform), I've taken claims about protein on them with a grain of salt.  The
reason for that is that Crude Protein does not measure protein at all...it
measures nitrogen content, and then that value is multiplied by 6.25,
because protein on average is 16% nitrogen. A feed could be loaded up on
gelatin, for example, and have a fantastic crude protein content, and yet
most of the nitrogen would end up on the ground in the urine--gelatin is
low-quality protein...the amino acid profile is extremely limited.

The classic example is the crude protein (equivalent) of urea.  I used to
ask my students if it was possible to have more than 100% crude protein in a
feed....they'd invariably answer no.  But, if you analyze urea using the
Kjehldahl nitrogen procedure, and multiply by 6.25, you get 281% CP.  Urea
is a chemical--it contains no protein whatsoever.

Protein quality is determined by the amino acid profile.  That profile is
one of the things that drives our choices of feeds in a ration. Corn and
soybean meal are a popular combination for a very good reason--corn is
deficient in lysine, and SBM corrects that deficiency very nicely.  Lysine
is usually what is called the first limiting amino acid, meaning it's the
first essential amino acid that usually runs out in protein synthesis.  When
it runs out, the body stops making proteins until more lysine is supplied by
the diet.

The theory behind defining some amino acids essential and some nonessential
is based on the premise that if the animal's body cannot make the amino acid
it must be supplied in the diet and thus is a dietary "essential".  The
essential amino acids are:  Phenylalanine, Valine, Threonine, Tryptophan,
Isoleucine, Methionine, Histidine, Arginine, Leucine, and Lysine in no
particular order of importance (I used that order because it's easy to
remember them that way:  the first letters spell out Pvt. Tim Hall).  Three
of these are in that paste that you got, Angie.

So, the idea behind the paste is a sound one; however, as you discovered, it
doesn't taste very good--individual amino acids tend to taste quite bitter,
because of their chemical make-up.  When they are put together as proteins,
the bad-tasting part is bound and so you can't taste it.  Moral of the
story--supplementing synthetic amino acids only works if the taste issue is
resolved.  There are no flavorings in the ingredient list at all to mask the
taste.

Lisa


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