ABSTRACTS
169
this period. At the end of the confinement period the flock
should be placed on a new range with an access to liberal
quantity of fresh green feed. Recovered adult fowls become
reservoir of infection for the young birds.
Cross-infection from wild birds to chick does not occur.
The process of immunization against coccidiosis by exposing
the birds to a moderate amount of infection in early life has
much to commend it to the experienced poultrymen, but to
the average breeder the measure of separate brooding and
rearing is the only safeguard. In case of annual recurrence
of the disease it is advisable to market the adult birds in the
spring and purchase new eggs or chicks from incubator ins-
tead. [H. N. R.]
Studies on the survival of Johne's bacilli.
R. LOVELL, M. LEVI, and J. FRANCIS (1944).
J. comp. Path. 54, 120-9
JOHNE'S bacilli are believed to survive for prolonged periods
outside the animal body, but this opinion is based largely
on the similarity of the organism to the tubercle bacillus and
not on any direct experimental evidence. The authors carri-
ed out a series of experiments designed to test the viability
of Johne's bacillus under a variety of conditions. These
experiments may be considered under three headings :
(A) SURVIVAL OF JOHNE'S BACILLI IN STERILIZED WATER
AT ROOM TEMPERATURE
The viability of Johne's bacilli was tested in sterilized dis-
tilled water, tap water and pond water containing dried mud.
Cultures of Johne's bacilli were mixed in varying amounts
with each kind of water and the mixtures stored in bottles
in a cupboard at room temperature. At approximately
monthly intervals, 10 c.c. samples were withdrawn from each
bottle, centrifuged and the deposit sown on Dunkin's medium
without dye. Duplicate cultures were made after treating
the deposit from an equal quantity with 10 c.c. of 10 per cent
antiformin for 15 minutes. Johne's bacilli were recovered
from each of the three waters after nine months, but not. after
13 months. The pH of the waters varied during the course
of the experiment between 6.4 and 6.8 for the distilled water,
7.1 and 8.0 for the tap water and 5.3 and 5.9 for the pond
water. The temperature fluctuated between 49º and 79º F.
(B) SURVIVAL OF JOHNE'S BACILLI IN NATURALLY INFECTED
INTESTINAL SCRAPINGS IN UNSTERILIZED RIVER WATER IN
THE OPEN AIR
Intestinal scrapings from an infected case of disease were
finely emulsified and mixed with river water collected
from a flooded meadow. The mixture was stored in a bottle
in the shade in a suitable part of the building, and samples
were withdrawn at monthly intervals and cultured after
treatment with antiformin. Johne's bacilli were recovered
from the water after 113 days' exposure. During the early
part of this experiment, the weather was very severe and
between the first and the 30th day the water was actually
frozen.
In a subsidiary experiment, in which a culture of Johne's
bacilli was substituted for the intestinal scrapings, the bacilli
were recovered only after the 1st day but not after the 30th
day. The authors are unable to give any explanation of
this anomalous result.
In another experiment, river water to which had been
added an emulsion of infected intestinal scrapings was placed
in two shallow earthenware bowls, 24 in. x 4 in. one of which
was kept in the shade and the other exposed to sunshine.
Johne's bacilli were recovered from the bowl kept in the
shade after 135 days but not after 163 days. From the
bowl kept in the sunny area, bacilli were isolated after 163
days and not after 218 days. During the period of the ex-
periment, the atmospheric temperatures varied between
20º and 64º F. and during the very cold weather the contents
of the bowl kept in the open were often frozen ; they were
never dry and the actual amount of the mixture varied with
rainfall.
(C) SURVIVAL OF JOHNE'S BACILLI IN NATURALLY INFECTED
FAECES EXPOSED TO ATMOSPHERIC CONDITIONS
Fluid faeces were collected from a natural case of disease
and placed in a shallow porous bowl similar in size to those
already described. This was placed in the open air exposed
to the full effect of sunshine and rain. The contents of the
bowl were sometimes fluid, sometimes frozen and at times
dried by the sun. The temperature varied between 26º and
74º F. Johne's bacilli were recovered for periods up to 246
days.
In another experiment, infected faeces were exposed to
air, a portion in a porous bowl and some in an enamel bowl.
The temperature fluctuated between 27º and 74º F. and
the contents of the porous bowl became dry towards the
latter part of the experiment. The contents of the enamel
bowl were, however, prevented from drying by the addition
of fresh water on one occasion. Under these conditions
Johne's bacilli were found to be viable in the porous bowl
after 152 days and in the enamel bowl after 208 days.
A number of subsidiary experiments carried out with fresh
samples of faeces yielded results more or less similar to those
above described.
In all the experiments, there was a progressive diminution
in the number of bacilli with the result that the number of
colonies obtained in culture towards the end was always less
than that at the beginning.
The viability of Johne's bacilli depends upon a number of
factors, such as the intensity of infection, temperature, mois-
ture content of the material, etc. ; of these the moisture con-
tent appears to be the most important.
Summing up their results, the authors conclude that they
afford ample confirmation of the generally held view regard-
ing the longevity of Johne's bacillus and lend strong support
to the measures often advocated for the control of the disease,
such as the breaking up of dung and manure, leaving in-
fected pastures ungrazed for over a year or more, draining
or fencing of ponds, etc.
[It may be pointed out that these results were obtained
in England under the conditions obtaining in that country
and they should not be interpreted too rigidly in their appli-
cation to this country where the climatic conditions are
different]. [L. S.]
Yeast as a protein supplement for pigs and its
relation to the appearance of rickets. R.
BRAUDE, S. K. KON and E. G. WHITE (1943).
J. comp. Path. 53, 161
THE authors in this article record the results of feeding
experiments with yeast as a protein supplement for fattening
pigs in peace-time. From a practical stand-point, the
results support the conclusions of many workers regarding
the high value of yeast as a protein supplement for pigs, but
as in the present experiments where the object was to ascer-
tain whether yeast could wholly replace the protein supple-
ment, some difficulties resulting from feeding large quan-
tities of yeast were observed.
Three series of experiments have been conducted and in
these the effects of yeast at the levels of 8 and 20 per cent
in the diet have been observed. A diet containing 8 per cent
of yeast, with no mineral supplements to make up a balanced
ration, was found to produce adverse symptoms in some of
the experimental animals, whereas an addition of extra cal-
cium supplement in the form of calcium carbonate (Ca con-