Summer may be a distant memory, but the consequences of
summer infertility in pig herds may only be coming to light now,
according to pig vet David Chennells.
"Infertility problems occur in summer when fertility dips due to
changes in light levels, depressed feed intakes from warmer weather
and water flows increasing the number of urinary tract infections.
These could have occurred anywhere in the pig's cycle and often the
problems are only found and realised in the autumn," he says.
But good management in the summer and autumn can help minimise
seasonal infertility, says pig technologist
Mark Hawe.
"Often autumn infertility gets the blame when nothing else can
be blamed, but it often comes down to management.
"Pigs naturally wouldn't be fertile during the autumn period due
to decreasing day length and also lighting intensity. This could
then have a knock-on effect on fertility and this includes pigs
coming into season, amount of time a sow stays in heat and
conception. Therefore, cranking up management now is vital to
detect any pigs returning," he says.
Because sow reproductive behaviour is affected by shortening day
length, Mr Hawe recommends making sure sows achieve at least 16
hours of daylight at an intensity good enough to read a
newspaper.
Whitewashing walls can also help improve the light intensity in
pigs building according to vet Alex Thomsett,
The George Vet
Group.
"Walls should also be whitewashed at sow eye level in buildings
where pigs are housed after weaning and at and around service. And
when using AI stalls, the compartment around the sow's head should
also be whitewashed to stimulate hormonal production.
"I have seen a marked improvement on reproduction in pig units
that have whitewashed their walls, this is because light hitting
the back of the eye stimulates hormone release which is linked to
fertility," Ms Thomsett explains.
And increasing heat detection to detect any individuals
returning following embryonic deaths in autumn is vital, says Mr
Hawe.
"You may see a few more early abortions in autumn, but these
often won't be seen and the animal will just return to heat. This
is why it is particularly important to look out for returns and the
best way to do this is to walk the boar down the dry sow house once
a day.
"When you do this, make sure the boar is not distracted by food
and don't give him access to more than four sows at a time.
Although this is time-consuming, it means any returns are not
missed."
He also recommends using ultrasonic scanners on sows at fours
weeks following service.
However, if abortions are being seen, don't assume it is a
seasonal problem, says Ms Thomsett. "When seeing abortion and a
high number of returns, talk to your vet to check it is not being
caused by some other reason.
"Also, check records to see if you experience a similar problem
every year or if it is a result of another underlying problem.
Maintaining summer and winter feed intakes to prevent sows entering
negative energy balance is also key to maintaining fertility."
Reduced numbers of sows holding to service can be overcome with
management changes, helping ensure as many sows as possible have
good sized litters.