Calculating YOUR CARBON Footprint Calculating ... - ClimateCHECK

RESEARCH
By Anupriya Dewan and
Sarah Van Engelen
Protein power
How amino acid imbalance can stimulate milk fat production
Altering levels of amino acids in
your herd’s diet may increase
fat and reduce milk’s protein
content, according to University of
Guelph research.
Professor John Cant has been
studying the effect of incomplete
amino acid profiles—diets with deficient
or imbalanced amino acid levels—on
fat production. He believes
altering a cow’s amino acid profile
may help position milk to meet
changing market demands.
“So far, we know amino acid
imbalance can affect milk fat,” says
Cant. “What we need to figure out is
the mechanism of how it happens.”
In cow milk, fat and protein content
are linked. Amino acids are the
building blocks of protein. An increase
in milk’s fat content means
reduced protein content. Cant believes
if a cow is fed a low amino acid
diet, it will not produce high levels of
protein in its milk. Instead, it will
make milk fat.
Altering milk’s protein content
without impacting the protein needed
by the cow to maintain body performance
can be difficult, says Cant.
Making sure the cow’s health is not
compromised by increasing fat content
is crucial.
Changing amino acid feed composition
is a challenge because microbes
in a cow’s stomach change the protein’s
composition during digestion.
The protein in the diet is not what
the cow is actually absorbing. Controlling
amino acid levels in the cow’s
diet is an important first step.
To do this, Cant will experiment by
feeding cows a low amino acid diet,
which will eventually be supplemented
by varying amino acid mixes
infused directly into the bloodstream
of cows. In some cases, the cows will
be infused by an amino acid mixture
completely deficient in a particular
amino acid. Histidine, an amino acid
known to play a critical role in milk
protein production, will be eliminated
first.
The impact amino acids have on
milk’s protein and fat levels vary. It is
believed a diet deficient in certain
amino acids could play a vital role in
milk production or an imbalanced diet
could alter blood flow to mammary
tissues. Likewise, a lack of certain
amino acids could change a cow’s
metabolism, resulting in fat being directly
deposited into the milk.
“Some nutritional changes in diet
can change the composition of milk
within a couple of weeks,” says Cant.
“We want to be able to adjust what
the cow is producing to match the
market’s demand without changing
the herd.”
Altering amino acids in your herd’s diet may affect
your milk’s protein and fat levels.
Anupriya Dewan and Sarah Van
Engelen are student writers with the
University of Guelph’s office of
research. Also involved in this research
are University of Guelph professors
Vern Osborne, Norm Purdie and
Carmen Chui and Anna-Kate
Shoveller from P & G PetCare.
Funding for this research was provided
by Dairy Farmers of Canada and
the Natural Sciences and Engineering
Research Council.
MilkPRODUCER | July 2008 | 37