Early in
the nineteenth century blue milk was an important problem, even more than
mastitis. Most authors of veterinary publications, especially in Germany, treated
mastitis and blue milk in one and the same chapter of diseases of milk, but
only blue milk was mentioned as affecting the economy of the dairy farm, or any
other farm at which milk was a commercial product for consumption, butter and,
sometimes, cheese.
I have
written about blue milk before (blog of september 18, 2013), but since I found
that the problem of blue milk has been intimately connected to the development
of the chemistry of milk and the microscopical detection of what we now call
microorganisms in milk, the problem of blue milk merits a more detailed
historical analysis.
One of the
first publications discussing blue milk is a French booklet, dating rom 1805 (Germinal an XIII) and is written by
P.Chabert and C.M.Fromage, both members of the Imperial Veterinary School of
Alfort of which Chabert was the director and Fromage a teacher. The title of
the booklet is “D’une altération du lait
de vache, désignée sous le nom de lait bleu” or “The alteration of cow’s
milk, designated as blue milk”.
Its
introduction contains an interesting statement: “most of the alterations [i.e.
changes in colour, consistency and other properties that make milk agreeable]
have not sufficiently been the object of observations of the Chemistry and the
Hygiene”. And although the authors gave much attention to the chemical background
and characteristics of blue milk (to be discussed next time), hygiene is left
out of their text, at least the hygiene that we in the 2015 recognize as such; I suggest that
chemistry and hygiene in 1805, as scientific disciplines, may belong to one and
the same activity.
What
follows is an essay of about 30 pages, dealing with blue milk only.
According
to Chabert and Fromage the characteristics of blue milk are the following.
Freshly drawn milk is normal, the cow looks healthy and the quantity of milk is
not diminished; nevertheless, after 12-18 hours the milk starts to become blue,
the surface of the milk and cream is covered with small small blue dots, the
size of a lentil, which expand to form a
closed layer on top of the milk in a pail or vessel. Butter and cheese are
affected in quality too, but the blue stain is mostly limited to the whey. The
phenomenon does not occur in the milk of all cows but sometimes in one out of
ten only; when the affected cow is kept separately, in another field, and its
milk not mixed with the normal milk, the problem seems to disappear, but when
the cow is brought back to the other cows it may appear again. As a passing
remark, Chambert and Fromage tell us that some people think that blue milk is
contagious, which may be based on the re-appearance of the problem after
bringing formerly affected cows back into the herd. Other people say that the
occurrence of blue milk may be reduced when you clean milk vessels with common
salt. Both remarks seem important to us, because of what was later found about
the cause and treatment of blue milk.
The authors
think that the problem of blue milk was seen for the first time in 1787 at an
abby near Evreux
and elder people think that it is a very old problem. It is certain, say the
authors, that it has been increasing
rapidly during the last 12-15 years (which is, for Chambert and Fromage, since
1790). Some farmers think that magic may be involved, or poisoning by enemies.
Dairy farms
close to a larger town may succeed in selling their milk when it is still fresh
and unchanged. Otherwise it should be given to pigs or dogs (who may not like
it).
Chabert and
Fromage discuss five possible causes. 1. The lay-out of stables and milk rooms.
2. The cleanliness of the milk rooms and the farmer’s houskeeping. 3. The
nature of the soil and the cultivation of the vegetation. 4. The forage. 5.
Wheather and climate. With regard to forage, they mention several plants that
may contain indigo-like compounds that may bne transferred to the milk unchanged
after ingestion.
Their main
conclusion is that the blue milk comes and goes without any regularity and that
it should be seen as a real disease because there is a change in the product
of the phenomena of life. The underlying cause may be a change in
physiology, which itself may be due to weakness of several organs, in
combination with what we now may call stress by sudden heat or cold. This may
lead to an altered action of the lymph, the blood vessels, the lungs and the
milk glands.
(to be
continued)
