The Rural Voice, 1991-09, Page 22Martin Mills Inc.
Lucknow Division
HOG — BROILER — LAYER
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Announcement
Martin Mills Inc. are now
dealers for Speedrite
Fencing Systems
COMPLETE LINE
OF ANIMAL FEED AND
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Martin Mills Inc.
Lucknow Division
Lucknow
519-528-3000
or
1-800-265-3006
18 THE RURAL VOICE
DIAGNOSTI
ENDING THE FALL ABORTION SYNDROME
by DR. S. E. SANFORD
VETERINARY LABORATORY SERVICES
About one per cent of sows in a
herd can be expected to have sponta-
neous abortions over the course of the
year. With the widespread adoption of
our modem indoor, intensive rearing,
total -confinement swine operations,
however, it gradually became apparent
that there was a noticeable and predic-
table sharp increase in spontaneous,
non-infectious abortions among sows
housed in these systems in the temper-
ate regions of most of the major swine
producing countries during the fall
months. In Ontario these abortions
start in September, increase in Octob-
er, reach a peak in November, and gra-
dually drop off in numbers thereafter.
Most of the abortions occur in
middle or late pregnancy, although it
is possible that earlier pregnancies
may have been terminated and foetus-
es resorbed or passed unnoticed.
Sows that abort are not sick. They do
not stop eating or have a fever. They
just abort and go on about their busi-
ness as if nothing had happened. The
aborted piglets are in perfect shape,
and if the abortion has occurred in late
pregnancy, some of the piglets may be
alive, but premature and unable to sur-
vive even with assistance.
This problem of fall abortions var-
ies from year to year, with only spor-
adic cases observed or reported some
years, and abortion storms occurring
in other years. The number of abor-
tions within a herd also varies from
one herd to the next. Some herds may
have up to 10 per cent of pregnant
sows abort in peak months (September
to December) while others have few or
no abortions. Medium and large herds
(150 or more sows) are more likely to
be affected. Abortions occur more
frequently during marked temperature
fluctuations, especially very low over-
night temperatures (around or below
freezing [0°C]) following a mild or
warm day (10 to 20°C).
This Fall Abortion Syndrome
seems to be related to a combination
of at least two different sets of circum-
stances.
• Although we treat our domestic
pigs (and they have responded/pro-
duced accordingly) as year round
breeders, it should be noted the wild
pig (from whom our domestic hog was
derived) is a seasonal breeder which
produces its piglets in the spring. Not
surprisingly therefore, female sex hor-
mones, especially progesterone — the
"pregnancy" hormone — in sows
(wild and domestic) are at their lowest
in August, September, and October
and rise to their highest in March.
It is also pertinent to note that this
autumn drop-off follows almost exact-
ly the reduction in the amount of day-
light hours that occurs after June 21st.
This then leaves a pregnant sow in a
somewhat precarious position with
respect to the maintenance of her
pregnancy and sets the stage for the
second set of circumstances.
• With the maintenance of preg-
nancy on a teeter -toner, any adverse
influence is likely to tip the scales in
the direction of termination of preg-
nancy (abortion). These influences
may include one or various combina-
tions of the following: low or fluctu-
ating environmental temperatures, ina-
dequate nutrition, discomfort, reduced
social contact with boars, reduced or
lack of opportunity for huddling with
other sows, and genetic predisposition.
Prevention of Fall Abortions
Solutions for the fall abortions
have been on an empirical basis, but
several things can be done.
• Artificial lighting can be main-
tained in the gestation barn to give 16
to 18 hours of light per day through
the late summer and fall. The inten-
sity of light should be about enough to
read a newspaper.
• Extra heat (up to 18°C) can be
provided to pregnant sows during the
fall months.
• Without overfeeding, the plane of
nutrition can be increased to compen-