1067-4136/04/3503- © 2004
Russian Journal of Ecology, Vol. 35, No. 3, 2004, pp. 205–208. Translated from Ekologiya, No. 3, 2004, pp. 235–238.
Original Russian Text Copyright © 2004 by Borisenkov, Kalinin, Vakhnina.
Many authors have noted seasonal changes in the
reproductive function of polyestral animals, for
instance, cows. It is supposed that the seasonal dynam-
ics of reproduction in cattle is governed by the condi-
tions of their keeping and feeding. At the same time,
there is evidence that the reproductive function of cows
depends on meteorological conditions (Vlasov, 1996).
The data on the effects of environmental conditions in
the North on the reproductive function are insufﬁcient.
It has been shown that metrorrhagia (uterine bleeding)
in cows in the Komi Republic occurs mainly in spring
(Belov and Sherenas, 1980). The calving frequency and
milk production in the area of Syktyvkar manifest sea-
sonal dynamics (Borisenkov, 1994).
This paper concerns the results of studies on the cir-
cannual rhythm of cow reproduction in the North.
Our studies were based on the archival
data on two dairy farms: Vyl’gort Biological Research
Station and the educational farm of the Syktyvkar Agri-
cultural Technical College (below, referred to as the
VBRS and SATC herds). For the VBRS herd, we used
data for the period from January 1, 1972 to December
12, 2000; for the SATC herd, for the period from Janu-
ary 1, 1972 to December 31, 1994. Both farms are
located near Syktyvkar (61
E), two kilome-
ters apart. The VBRS herd, on average, comprised
50 milk cows of the piebald breed; the SATC herd,
180 cows (26.5% of the Ayrshire breed and 73.5% of
the piebald breed). In both herds, artiﬁcial insemination
was commonly used throughout the year (depending on
the estral cycle). The sperm for this purpose was taken
from the same bulls in the Komi Republican Livestock
Values of the index of geomagnetic activity (Kp)
over the period from 1932 to 2000 were taken from the
World Center on Geomagnetism, Kyoto (Japan).
Construction of time series.
The archival data were
put into an EXCEL electronic spreadsheet. The total
numbers of calvings during each month over the entire
period under study was counted. Since cattle stock con-
siderably varied during this period, the initial data on
calving frequency were converted into percentages (the
number of calvings in a herd during a year was taken as
100%). The resulting temporal series were smoothed
with a ﬁfth-degree polynomial to remove “noise.” The
seasonal dynamics of calving frequency were assessed
by plotting the dependence of the total number of calv-
ings over the entire study period on the month of the
year and the dynamics of conception frequency, by
shifting the plot of calvings to the left along the tempo-
ral scale by nine months (the average gestation period
in cows). The Kp index dependence on the month of the
year was also plotted.
Analysis of time series.
The periods of ﬂuctuations
of calving frequency in each herd were assessed by Fou-
rier spectra. The plots were derived by analyzing temporal
series listed in Fig. 1 using the STATISTICA 5.0 software
Seasonal Dynamics of Cattle Reproduction in the North
M. F. Borisenkov, A. I. Kalinin, and N. A. Vakhnina
Institute of Physiology, Komi Scientiﬁc Center, Ural Division, Russian Academy of Sciences,
ul. Pervomaiskaya 50, Syktyvkar, 167982 Russia
Received April 10, 2003
: North, cow, calving frequency, conception frequency, seasonal dynamics, geomagnetic activity.
1972 1975 1978 1981 1984 1987 1990 1993 1996 1999
1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994
Time series of calving frequency in the herds of the
(a) VBRS and (b) SATC farms located in the vicinity of