•—Lancaster Farming, Saturday, June 6,1981
.6
Should you feed
free choice minerals?
Tony R. Rickard
Assistant Professor
Department of
Dairy Science
COLLEGE PARK, Md. -
Although minerals are a small part
of the ration, they are essential for
optimum health and production of
dairy cows. At least 15 mineral
elements are required by dairy
cattle.
How should these minerals be
fed?
There are differences of opinion
among dairymen, nutritionists,
veterinarians and feed salesmen
as to the ability of dairy cows to
select minerals according to their
needs when offered free choice.
But more and more evidence in
dicates there is little correlation
between the amount an animal
eats and its requirements.
Comments, often made by
dairymen to justify feeding
minerals free choice are “The
cows are eating a lot of the mix, so
they must need them,” and “I just
feel a whole lot better when I know
they are available to my cattle.”
Granted, certain individual cows
may consume large quantities of
the mix.
Several universities have
evaluated free choice or cafeteria
style feeding of minerals. In a
South Dakota study cows are fed
either corn silage or alfalfa hay.
The same concentrate mix was
offered to both groups (with no
added minerals), and minerals
were offered cafeteria style. There
were individual compartments for
calcium, phosphorus, potassium,
sulfur, trace minerals, bicar
bonate, bentonite, salt and an
iodine mix. Also vitamins A, D and
E were available.
Calcium consumption was not
different between groups even
though alfalfa fed cows were
getting three times their
requirement, and the corn silage
fed cows were calcium deficient.
Cows fed com silage did consume
more potassium than those fed
hay, but not enough to fulfill their
requirements. If cows are able to
select for mineral needs, there
should be a difference in mineral
consumption. Obviously, this was
not the case.
In a second trial all cows were
fed the same roughages (free
choice com silage and 3.5 lbs. of
alfalfa hay) and the same con
centrate mix. Half of the cows
were force fed recommended
levels of minerals, and half were
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not. Both groups had access to the
free choice mineral and vitamin
feeders.
The analysis showed that cows
force fed the recommended
amount of minerals consumed
more than those offered free
choice minerals. Calcium and
potassium, the two minerals which
differed most between rations,
were consumed in larger amounts
by the force fed group even though
levels were adequate m their basic
diet. These results indicate that
voluntary intake had little to do
with actual need.
Results similar to the study cited
above have been reported by
researchers in Minnesota, Cornell
and England.
Research clearly indicates that
dairy cattle are not capable of
deciding which minerals, or the
amount, they need for production
and health. Mix the minerals with
the concentrate portion of your
ration or blend them into a com
plete ration to insure all cows
consume enough to meet their
needs.