xt7f4q7qq211 https://exploreuk.uky.edu/dips/xt7f4q7qq211/data/mets.xml   Kentucky Agricultural Experiment Station.  journals kaes_circulars_004_446 English Lexington : The Service, 1913-1958. Contact the Special Collections Research Center for information regarding rights and use of this collection. Kentucky Agricultural Experiment Station Circular (Kentucky Agricultural Experiment Station) n. 446 text Circular (Kentucky Agricultural Experiment Station) n. 446  2014 true xt7f4q7qq211 section xt7f4q7qq211 C I I I  
0mI“Il0l1 Causes of lf2l[l·3ll0ll ln ~   '
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Butterfat Content of M'|k and Cream
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MILK ANI) CREAM are usually bought and sold on the basis of per
cent of butterfat contained. Butterfat content is measured by the ·
Babcock test, a simple test which when properly done offers little
chance for error.
lt is natural for some variation to occur in the butterfat content of
inilk and cream from a herd of dairy cows, and therefore in the "test"
of the milk or cream. The purpose of this circular is to explain the
more common causes of this variation. ·
Reasons for Differences in Milk Tests
Breed of cows in the herd
Percentof butterfat in tl1e milk differs considerably from breed to ‘
breed of dairy cows. Usually Jersey milk is richest in butterfat and
Holstein milk contains the least. The butterfat content of the milk of
the leading dairy breeds ranks in the following order: jersey, Guern-
sey, Ayrshire, Brown Swiss, and Holstein. In amount of milk pro-
duced usually the ranking is exactly reversed. Therefore, little differ-
ence exists between the breeds in butterfat [production. Obviously, if
a number of Jersey cows are added to a non-_]ersey herd the butterfat y
test of the milk produced will tend to rise. On the other hand. il` _]ersey _
cows are replaced by Holsteins more milk will probably be produced,
‘ but the butterfat test will very likely be lower. i
The individual cow
(lows of the satire breed often diller considerably in the butterfat
test of their milk. lt is not uncommon for the milk of one Holstein
tow to test 2.8 percent butterfat while that from another Holstein in
the same herd, receiving the same feed and care. may test 4.0 percent.
ln the same way _|ersey cows in the same herd normally may produce .
milk ranging from ·l.utterl`at. _
Richness of the milk
Factors which affect tl1e test of the milk also affect the test of tl1e
light rream. A separator delivers approximately the sa111e quantity of cream
rrtcst from a given quantity of milk regardless of tl1e test of the 111ilk. Tl1e . A
$?**'“` (lllliCl`(‘ll(`Q is i11 the test of the cream. A separator adjusted to deliver  
f 3 l g

 lll percent cream from 5 percent milk will deliver approximately 32
percent cream from Al percent milk. when operated in exactly the same
manner.
Temperature of the milk  
.·\s milk cools it becomes increasingly diliicult to separate it elli-
ciently. Cold cream does not How so readily as warm cream, and is
· inclined to clog the cream opening. This results in a smaller amount
, of richer cream and a loss of butterfat in the skimmilk.
Operation of the separator
Adjustment.- A properly adjusted and operated cream separator
· delivers skimmilk testing less than .02 percent of butterfat, which is
I negligible. By adjusting a simple device in either the skimmilk or
cream opening, the operator can control the amottnt of cream or skim-
milk delivered by the separator. The result may be richer cream anal
more skimmilk, or vice versa, regardless of the test of the milk of the
herd. .
Speed of the machine.- Separators are designed to operate at a
. _ certain speed. Slower speed results in a larger volume of thinner cream
l l and a loss of btttterfat in the skimmilk. Higher speed causes a smaller
4 volume of richer cream and more skimmilk.
Rate of inilow.- Usually this is regulated automatically by a
lloat. lf for any reason the rate of inflow is too slow the result will he
a richer cream. lf the separator is fed too fast the milk is forced from
the bowl before the centrifttgal force has been sufliciently applied and
the result will be lower-testing cream and loss of butterfat in the skim- -
. milk.
i Vibration of separator bowl.- \Vorn bearings, an unbalanced
bowl, or failure of the separator to be properly leveled may cause the
bowl to vibrate. This results in a lower-testing cream and a loss of
butterfat in the skimmilk. l
Cleanness of the separator bowl.-\tVhen separators are washed .
so infrecjuently that curd particles or separator slime partially clogs
the bowl. ellicient skimming is not possible. .·\ clogged bowl causes ttttt ‘ 
much skimmilk to be forced through the cream opening, which results
in a lotv—testing cream. Q
Amount of Hush-water used.- ll the cream spout is allowed to
drain into the cream just enough water should be used as a rinse to
cause a very small amount. to come from the cream spout. lt will
greatly reduce the chance for variation in the butterfat test of the
cream if the same amottnt of water is used each time.
Lexington, Kentucky 777777 I ATT rWTTE€?j;;gm1;Q,1947
Cooperative Extension Work in Agriculture and Home Economics; College of Agriculwfc ·
and Home Economics, University of Kentucky, and the United States Department of Agri-
gjlljgutgejnpgolpleggtggygig34`homas P. Cooper, Director. Issued in furtherance of tlitlopltfgig Q
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