ABSTRACTS
Menstruation frequency and its relation to concep-
tion in dairy cattle: GEORGE W. TRIMBERGER
(1941). Jour. Dy. Sci. 24, 819
MENSTRUATION and its relation to conception varies
considerably in mammals. The time in the sexual cycle
when monstruation occurs varies between species and
sometimes within a species. Human menstruation
extends over an exceptionally long period and usually
starts midway between successive ovulations. It seems
to be largely a function of the uterus although other
reproductive organs share to some extent the vascular
congestion exhibited by the uterus at menstruation.
There seems some disagreement as to whether menstrua-
tion in the human indicates positively that fertilization
has not taken place.
A pronounced flow of blood continues for about ten days
in the bitch, immediately after which coitis is most suc-
cessful. Blood is not generally present in the proestral
discharge of the mare. Ewes usually show no discharge,
as is always true of the sow.
The cow menstruates usually two days after heat; the
uterus is involved as is also that portion of the vagina
above the urethra.
Some authors report that the
appearance of the menstrual flow after coitis is a positive
indication that conception did not take place; others
do not accept this as fact while they feel it is a valuable
sign.
Data for this study were collected at the University
of Nebraska herd. Menstruation refers to the external
discharge of a bloody fluid, usually mucus mixed with
blood, from the genital tract following oestrus. Obser-
vations were made on 100 heifers and 100 cows which
were not served during oestrus and 100 heifers and
100 cows which were ' inseminated ' during oestrus.
The frequency and amount of discharge was noted and
recorded; the amount being rated as slight, moderate,
or pronounced. Observations were made at six regular
intervals daily for five days after oestrus.
The 100 heifers not served all menstruated, whereas
of the 100 cows not served only 61 menstruated. Mens-
truation occurred in 81 of the 100 heifers bred at oestrus.
The number of conceptions which occurred in this group
of 100 heifers was 61 of which 52 or 85.25 per cent
menstruated. Of the 39 heifers of this group which did
not conceive, only 74.36 per cent menstruated. Of the
100 cows bred at oestrus, 61 menstruated and 72 con-
ceived of which 50 or 69.44 per cent menstruated. Of
the 28 cows of this group which did not conceive, only
11 or 39.29 per cent menstruated.
It appears, on the basis of this study, that the common
belief among stockmen that menstruation following
service indicates failure of conception is erroneous.
[J. N. W.]
The causes of stillbirth in swine and an attempt to
control it: S. A. ASDELL AND J. P. WILLMAN
(1941). Jour. Ag. Res. 63, 345.
APPROXIMATELY 5 to 8 per cent of the young pigs born
in the United States are still-born, that is they die just
before or during birth. One report each for Slovakia and
New Zealand indicate 3.2 and 9.6 per cent respectively
of still-born pigs in those countries. McPhee and Zeller,
it is reported, found that stillbirth was related to litter
size, both the smallest (1 to 2) and the largest (15 or
more) litters showing the highest mortality at birth.
Accurate records and the autopsy of still-born pigs,
together with the injection of pituitrin in certain cases
to prevent delayed birth, were practices followed by the
authors in carrying out the present study with Berkshire,
Chester White and Duroc-Jersey pigs at Cornell Uni-
versity. Mummified embryos were not counted.
Of 1,882 pigs born from 1930 to 1935 inclusive, 6.6
per cent were dead. Little breed difference was found.
The percentage of stillbirths increased with size of litter
due, the authors believe, to the increased duration of the
birth process. The percentage of stillbirths also increased
with an increase in the age of the sow. A seasonal varia-
tion in stillbirth rate was found, with 9.2 per cent in the
spring and 4.9 per cent in the fall. A slightly higher
death rate of females suggested a sex difference in sus-
ceptibility.
An incomplete tendency for still-born pigs to be
immature was noted. Over one hundred pigs were
dissected and an attempt made to determine the
cause of death. The authors say that some cases could be
little more than guess work because of the difficulty, for
example, of knowing what size of an organ is lethal.
They report the causes of death, however, as follows:
immaturity, 8; disproportionate organ weights, 18:
pathology, 19: endocrine disturbance and oedema, 19:
deformities of skeleton, 5; accidental death, 13; and
no obvious reason for death, 45. No Brucella suis
infection was found in the herd during the study. The
extent to which death was due to hereditary causes cannot
be stated. Histological examination of lung sections
showed that in many cases death occurred before infla-
tion. This, together with the higher incidence of death
in the latter half of large litters, indicated quite clearly
that the prolonged birth process was an important cause
of the trouble.
Starting in 1936, pituitrin was used for five farrowing
seasons to observe the affect of hastened birth. At
first 2 c.c. U. S. P. IX and later 1 c.c. U. S. P. XI pituitrin
was injected subcutaneously in the soft part of the neck
as soon as the first pig was born. During this time the
mortality rate of 1,148 pigs was 2.9 per cent, indicating
one possible means of controlling stillbirth in pigs. A
check on these findings, however, for five farrowings
starting in the fall of 1938, consisting of the injection with
pituitrin of each alternate sow, did not confirm this
means of reducing stillbirth. During the check period
4.3 per cent of 352 pigs born to injected sows and 2.4
per cent of 545 pigs born to sows not injected were still-
born. [J. N. W.]
Variations in bull semen and their relation to
fertility: E. W. SWANSON AND H. A. HERMAN
(1942). Jour. Dy. Sci. 24, 321
WITH the wide-spread practice of artificial insemination
in dairy cattle goes the need of determining the fertility
and longevity of bull semen at the time of collection.
Different workers have used different criteria, such as
initial motility, duration of motility, rate of glycolysis,
initial respiration rate, examination of the stained sper-
matozoa, the proportion of abnormal spermatozoa, pH of
the semen and spermatozoan head length. The variation
in the performance of different bulls, however, must not
be overlooked in fixing limits for any such factors. Normal
variations in the semen of several bulls and their relation
to fertility are reported herein.
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