ABSTRACTS
Study on the mortality rates of calves in 335 herds in England and Wales
(together with some limited observations for Scotland). R. LOVELL
AND A. B. HILL. (1940). J. Dairy Res. 11, 225.
P REVIOUS observations by two independent observers on herds in Ayrshire (Scot-
land) showed an annual mortality of 20-22 per cent with 27 per cent in spring and
8 per cent in autumn calves.
In the present survey the total number of live births reported in 335 herds (14,000
cows) in England and Wales during the years 1936-37 was 25,209 (12,665 male and 12,544
female) ; the mortality per 100 livebirths was 4.4 male and 5.5 female (the number for
bull calves is low owing to disposal at an early age to butchers) ; the number of still-
births was 4.7 per 100 total births ; the number of abortions was 6.5 per 100 pregnan-
cies. The total losses (deaths, stillbirths and abortions) were 14.3 per 100 pregnancies.
The corresponding figures for 47 herds (1,750 cows) in Scotland were : mortality
per 100 livebirths, 4.0 male and 11.4 female ; stillbirths 2.9 per 100 total births ; abor-
tions 5.2 per 100 pregnancies; and total losses 15.1 per 100 pregnancies. In both
surveys roughly one in seven pregnancies failed to produce an adult animal.
In determining the rates of losses in separate herds, half the herds had less than 4
per cent of total losses on the average ; one herd in five lost more than 10 per cent of its
liveborn calves, one herd in ten had more than 10 per cent of pregnancies ending in still-
births and one herd in five more than 10 per cent end in abortions.
With regard to the seasonal incidence of mortality, the Scottish rates for female
calves were 12.2 per cent for the first half and 3.7 per cent in the second half of the
calendar year ; the English rates for the first and second halves of the year were : males
5.2 and 3.7, females 6.2 and 5.0 per cent. The high mortality rate in Scotland is entirely
due to large numbers in the first half of the year. Factors inimical to calf life have a
greater influence in this period but these factors do not affect the products of conception
in utero.
There was no great variation in mortality in the different regions from which the
data were collected, except for a suggestion of a higher rate in Northern England. The
mortality rates are also not seriously affected by size of herd. The average female
death rate in herds under 20 was 6.7, and in herds over 20, 5.4 per cent.
Colostrum was suckled in 71, given by bucket in 27 and not given in 2 per cent of
240 herds ; the relative death rates for these classes were : male 100, 119, 131, and
female 100, 124 and 141 respectively, the differences being significant for the first two
groups of females only. In methods of feeding calves, more calves died when fed diluted
milk by bucket (5.8) than when suckled (4.8) or bucket-fed undiluted (4.7) ; statisti-
cally the differences are not significant.
Nearly half the deaths of female calves took place in the first week of life and three
quarters in the first month.
[W. L. D.]
Microbiology of silage made by the addition of mineral acids to crops rich
in protein, II. The microflora.* A. CUNNINGHAM AND A. M. SMITH.
(1940). J. Dairy Res. 11, 243.
T HE addition of mineral acids to green vegetable matter so as to reduce the pH below
4.0 successfully preserves even highly nitrogenous materials such as leguminous crops.
This is the A. I. V. process of silage making. The acid treatment however does not
completely inhibit the growth of bacteria and other micro-organisms. The organisms
which can grow in A. I. V. silage must be those which can initiate growth below pH 4,
and it was anticipated that such silage would contain some unusual types.
* The first paper of this series appeared in Zbl. Bakt., 1939, II, 100, 394-408, not at present
able to be consulted.
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