The midland journal. (Rising Sun, Md.) 1885-1947, 1926-10-08
Milk Secretion
Process in Cow
Novel Experiment Conduct
ed at Federal Dairy Farm
at Beltsville.

prepared by the United States Department
of Agriculture.)
A novel experiment to determine
whether the milk in cows udder is
manufactured during the few min
utes required for the milking proc
ess, as is generally taught, or wheth-
er 1t is secreted continuously and col
lected in the udder previous to milk
ing, was conducted recently at the fed
eral dairy experiment farm at Belts
vile, Nd, by w. w. SWEET, bureau Of
dairy industry, United States Depart
ment of Agriculture.
A rather general belief persists
among teachers and other professional
men in dairy cattle and veterinary
work, says Mr.. SWEET, that the inter-
nal capacity for storing milk in a
cows udder is not more than q half
pint to each quarter. Since many cows
yield much more than that amount. it
Is taught, therefore, that the milk
must necessarily be manufactured
during the process Of milking, and
that 1t does not exist as milk until
the mammary gland Is stimulated by
the milking operation.
Capacity Of Cows Udder.
In these tests IL was found, how
ever, that cows udder is capable
of holding from IL to 20 quarts Of
milk instead Of only a quart, as is
quite commonly taught. For the tests,
two cows were killed, their udders inn
mediately removed and mounted on
framework in position for milking.
One of the cows had normally been
giving about twelve pounds at milk
ing. A total of 1927 pounds of milk
was drawn from her udder after all
body connections had been severed,
showing that more than IS per cent Of
her production was stored in her ud-
der at the time she was slaughtered.
The post-mortem milking of the sec
ond cow yielded practically 80 per
cent of her normal production. In her
case milking was more difficult and
all the milk was not drawn as was
shown by the considerable quantity
which gushed forth when the udder
was later cut open.
A further indication of the enor-
nous capacity of a dairy cows udder
has been shown by the quantity of
liquid which is often possible to in
ject into detached udders being pre-
pared for laboratory study. Mr.. SWEET
says that 1t is not uncommon to in
ject the equivalent of three to five
gallons of milk, depending on differ
ent characteristics of various udders.
Continuous Process.
These few tests, while not to be re-
garded as conclusive, would indicate,
says Mr.. SWEET, that milk secretion is
to considerable extent a continuous
process, and that large proportion
Of the milk secured at any milking is
collected and stored within the man.
mary gland before milking is COM
menced; also that liberation Of the
milk from the gland is not dependent
either upon a nervous mechanical
stimulation or upon muscular contrac-
ton, since all body connections had
been severed before the post-mortem
milking was performed.
The mammary gland, obviously, is
one Of the most important parts of the
dairy COW, yet Its internal anatomy,
its capacity, and Its performance are
but little understood, says Mr.. SWEET.
The project now being conducted by
the bureau of dairy industry to deter
mine the relation Of the conformation
and anatomy Of the dairy cow to her
milk and butter-fat producing capacity,
has been developed to include an ex-
tensive consideration of the mammary
gland. This newest phase in the study
of the mechanism of the dairy cow
promises to be most interesting and
very productive of valuable informa-
ton.