J. B. POLDING
151
TABLE VII
Age at which foetuses are aborted
Class
European (European records)
.
.
.
.
.
European zebu, crosses
.
.
.
.
.
.
Buffaloes
.
.
.
.
.
.
.
.
.
Population
observed
95
102
103
Age of foetus in months
3
5
4
3
4
6
8
3
5
14
13
8
6
15
22
14
7
24
26
22
8
31
29
26
9*
27
Figures = percentage abortions occurring at the months shown
*Buffalo's mean period of gestation = 10½ months
TABLE VIII
Abortion rate in various grades of cross-breds
Class of animal
Friesian (Indian records)
.
.
.
.
.
.
.
.
⅞ „ . . . . . . . . . . . .
¾ „ . . . . . . . . . . . .
⅝ „ . . . . . . . . . . . .
½ „ . . . . . . . . . . . .
¼ „ . . . . . . . . . . . .
Indigenous . . . . . . . . . . . .
Population
18*
108*
329
152
464
134
275
Number of
aborters
2*
8*
21
9
14
2
4
Abortions per
cent
11.1
7.3
6.4
5.8
3.0
1.5
1.4
Mean annual abortion rate total population = 3.3 per cent
*Mean of three years ; the remaining figures mean of four years
(Figures by kind permission of the Director of Military Farms)
Tables IV to VIII give some abortion statistics of Indian bovines, which for purposes of com-
parison are grouped into : European zebu crosses, pure zebu cohabiting with European crosses, pure
zebu, and buffaloes. An attempt has been made to abstract from these figures some concept of
relative susceptibility ; for this purpose the mean expectation of loss of calves due to abortion,
during the working lifetime of 100 random animals, has been worked out. Thus a susceptibility
figure has been obtained by multiplying the mean expectation of loss of calves per aborting animal
(Table V, column 7) by the mean expectation of unrepeated abortion during the lifetime of 100
random animals (Table IV). These figures are shown in Table V column 8, and, if the smallest is
taken as unity, the relative susceptibility of zebu, buffaloes, cohabiting zebu, and crosses is 1.0 :
1.38 : 2.44 : 6.79, respectively. These results, together with the data of Table VIII, suggest that
the greater the proportion of European blood in the animal, the greater is its susceptibility to bru
cellosis. At first sight, moreover, the buffalo appears to be more susceptible than the zebu. In
point of fact, however, most of the buffaloes observed were cohabiting with crossbreds, so it is likely
that there is little difference between the susceptibility of indigenous pure-breds.
Certain other records suggest either that the susceptibility of Indian cattle is decreasing, or that
better animal management is limiting dissemination of the disease. For example, the reports of the
military farms (northern circle) from 1932 to 1939 show a progressive annual decrease in the abor
tion rate ; a decrease which runs parallel with improvements in housing and management. On the
other hand, since 1939 there have been indications that, in the busier farms at least, the rate has
increased, an increase which has coincided with over-crowding and the unavoidable lessened atten
tion due to the wartime expansion. It seems probable, therefore, that good management, rather
than reduced susceptibility, was the reason for the earlier decrease. Another example of decreasing
incidence is to be found in the Punjab grantee farms. In 1923 the mean abortion rate, calculated
from a single random observation of five of these farms was 3 per cent of 1264 animals, while in 1939
the figures had fallen to 1 per cent of 835 animals. Here again, good husbandry is probably the
cause of the diminution.