Oxford Democrat., 1921-05-17
Variations In Butter.Fat Tests.

The butter.fat test OF milk is subject to
variations because OF soma Of the follow
ing factors: Breed of COWS, period OF
lactation, portion OF milk drawn, ner-
vous excitation of the COW, improper
sampling of the milk and improper
manipulation OF the Babcock test by
which the fat content of milk Ii COM
monty determined.
The four chief dairy breeds, In the
order of their milk-fst content, from
highest to lowest, stand In the following
order: Jersey, Guernsey, Ayrshire and
Holstein- Freisisn. Within each breed
are individual COWS whose milk will test
higher or lower than the breed average.
In general ~ the lactation period ad-
vances the fat test of the COWS milk in
creases.
The milk first drawn from q COW is
very much lower In fat content than the
last drawn or "strippings."
greatly excited 1t may affect the test Of
her milk 20 that it may be higher or low
er than normal. II the milk sample
saved for testing is not taken from .
we'll mixed pail or can of milk the test
made will not be truly representative Of
the per cent fat iD the milk.
The Babcock test should be correctly
performed in order to obtain accurate
results. Careless operation will result
In tests which may be higher or lower
than they should be.
In connection with the butter.fat test
of cream there are . number Of factors
which tend to bring about differences In
cream test from time to time, and some
of the factors are not always given the
attention that should be given them.
They are az follows:
Method of separation employed,
whether gravity or centrifugal; test OF
milk separated; speed of separator bowl;
bowl out OF balance; rate of inflow OF
milk; amount of liquid used to flush
bowl; dirty condition of bowl; and
manipulation of Babcock test.
In the old-fashioned method of cream
ing where the milk is set in pans or
deep, small l-diametered cans, to allow
the cream to rise, considerable variation
will be found In the test Of the cream
due to varied conditions. In the GEN.
trifugal method of Dreaming less varia-
tion In cream tests may be expected II
conditions are uniformly the same. The
following conditions apply to the hand
separator.
II the milk varies in test from time to
time the cream separated from 1t will
vary In test per cent for each one-tenth
per cent variation In test.
If the milk is too low In temperature
the test of the cream will be higher be-
cause the cream outlet becomes clogged.
II the speed of the bowl is increased
beyond normal the test of the cream will
be increased and II speed is below nor
NAL the opposite effect is obtained.
When the bowl 10 out of balance, due
to the separator being out of level, the
test of the cream 10 decreased.
The faster the milk flows into the
separator the lower the cream will test.
II just the same amount OF skinned
milk or water is used to flush the seps-
rator bowl each time at the end OF the
run, the test Of the cream will not be
affected, but II varying amounts are used
the test will be affected.
In the case of cream az with milk I'm
proper ssmpling and careless manipula-
ton of the Babcock test will result In
inaccurate cream tests being obtained
Prof. L. N. Dorsey.