They might seem like good girls who would like a nice, well-behaved
boar, but to turn on gilts, producers should let them date the bad boys
of the swine world.
“You need the most aggressive, dirty, angry boar that you can get,”
English swine breeding expert Keith Thornton told Manitoba pig farmers
at the Manitoba Swine Seminar.
Producers try to stimulate early puberty in gilts by exposing them to
sexually mature male pigs. Exposure to boars speeds up the number of
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gilts coming into estrus and strengthens the signs of heat.
Thornton said many North American farmers use tame, well-mannered boars
because they’d rather lead along a friendly pig than fight with a
nasty, combative one.
It might be easier, he added, but that kind of boar doesn’t excite the
gilts.
“It’s like a tame dog you’re moving along. It’s just not having the
impact or the effect,” he said.
“(A sow) needs the stimulation, it needs the chomping, it needs the
smell, it needs the sound.”
Producers who have trouble handling the randy beasts should consider
using a mobile cage or harness.
Thornton said many swine-breeding companies have been developing
aggressive boars to maximize sow responsiveness. Some have brought in
genes from a particularly aggressive Chinese breed.
There should be five to seven sexually mature boars of various ages for
every 1,000 sows in an operation, Thornton said.
Mixing boars with gilts has the biggest effect on females, but
nose-to-nose exposure through a gate is more effective than no exposure
at all.
Putting a boar and about 20 gilts into a pen together for 10 minutes is
effective. There should be enough room in the pen for the boar to be
able to circulate amongst all the females.
Producers need to know when their gilts come into heat because that
helps determine when to inseminate them. They can be sorted into groups
based on when they first went into heat.
That’s why it’s important to keep the boars housed away from the gilts.
The smell of the boars can stimulate the gilts into signs of heat when
no barn staff is around, which makes it hard to accurately record the
female’s response. The boars should either be in a separate room, or
downwind from the gilts near an exhaust fan.
Young gilts aren’t hurt by early boar exposure, but producers who want
females to be well synchronized should keep the boars away until the
females are about 150 days old.
Thornton said producers should look for boars that will grab the sow’s
attention and get it excited.
“It’s aggressive, it’s chomping, it’s looking at the animals.”
