ABSTRACTS
255
For the production of milk it is essential to supply in the food those amino-acids
present in the milk protein which cannot be synthesised in the animal body. From the
data given it is evident that certain food-proteins, viz., proteins in the form of spring
grass, silage from summer grass, low temperature dried blood meal, and pea-meal re-
semble milk-protein in their content of amino-acids more closely than do linseed cake,
decorticated earthnut cake, maize or oats. For maximum milk production 0.5 lb.
digestible true protein is required per 10 lbs. milk, but with proteins of high biological
value, which supply all the essential amino-acids in the proper proportions for milk
production, the amount does not exceed 0.44 lb. digestible crude protein per 10 lbs. of
milk.
It is uncertain whether any part of the protein can be replaced by non-protein
nitrogen. [N. C. D. G.]
The isolation of Brucella abortus from the milk of cows with negative
blood reactions to the agglutination test. DOYLE, T. M. (J. Comp. Path. Ther.
49, 320-327)
A LARGE number of samples of milk were tested from cows in Brucella-infected
herds that failed to give an indication of infection on their blood test. Blood and
composite samples of milk were collected from all cows under examination and sero-
logical tests of the blood were carried out in order to preclude the examination of milk
from positive cases. Milk from each non-reactor cow was centrifuged and 2 c.c. of
the cream and the deposit inoculated intramuscularly in two guinea-pigs. The milk
whey was tested for the presence of brucella agglutinins. Cultures were made, on
liver agar, from each spleen of guinea-pigs about the forty-fourth day after inocula-
tion and incubated for ten days under 10 per cent CO 2 at 37°C. An agglutination
test of serum from each guinea-pig was carried out. The antigen employed was made
from a seventy-two hour old " smooth " non-thermo-agglutinable strain of Brucella
abortus on liver broth culture and the density was adjusted by the addition of a forty-
eight hour old washed liver agar growth. A water-clear whey was prepared by clott-
ing centrifuged milk in the incubator to which rennet was added. The examination
of 309 milk samples carried out by guinea-pig inoculation revealed the presence of
Brucella abortus in samples from two cows whose blood proved negative on aggluti-
nation test. In one case milk from a positive case was tested from which the organism
was isolated. One sample of whey yielded a titre of 1 : 100, but in this case the milk
proved negative on guinea-pig test. With a positive blood titre of two test guinea-
pigs the cultural examination of their spleens was negative. The author carried
out serological tests of 684 cows during the course of this work and the average herd
infection was found to be about 35 per cent. The possibility of the infection of the
udder of cows with Br. abortus showing negative or low titre is discussed. [J. A. I.]
The breeding media of some common flies. THOMSEN, MATHIAS AND HAMMER,
OLE. (Bull. Ent. Res., 27, 559-587)
THE observations recorded in this paper were carried out in Denmark, the two
main species of flies concerned being the house-fly Musca domestica and the stable-
fly Stomoxys calcitrans. Under natural conditions, the former was found to breed,