|| Is motherhood going
downhillamong sows, at least? Is that one reason why piglet mortality has
increased lately, despite an overall downward trend?
Research and good animal management have significantly improved piglet
survivalmortality is down from 35 percent in 1924 to 13 to 15 percent
last year. But those losses, from $130 to $330 million a year, are still a
significant national problem.
In this country, about half of piglet deaths are from being crushed by their
Donald C. Lay searches for reasons as he watches 2-pound piglets get crushed
when their half-ton mothers lie down and roll over for a good nap.
Even if he slaps a sow lightly on the back to alert her and save some piglets,
others rush in, only to be crushed as she lies down again. The sows do this
despite the deafening cries of their doomed piglets.
Lay is ARS' latest and second farm
animal behaviorist, after Julie Morrow-Tesch, whose work is described in the
article on page 4. Their research is part of the ARS National Program
"Animal Well-Being and Stress Control Systems," begun in 1994. The
program aims to find solutions to problems like piglet mortality through
observing animal behavior.
Observations and research show that the first day of life is when most piglets
are crushed. Lay has watched some sows lie down peacefullyand almost
continuallyfor 11-½ out of 12 hours after giving birth. That almost
guarantees piglets will make it through half of their most vulnerable period.
Why then, Lay wondered, are other sows so restless that their movements
endanger piglets in those first 12 hours?
Seeing sores on the sows' hindquarters and legs, Lay concluded that the
flooring was uncomfortable to them. He gave them an analgesic (pain-killer),
and they rested peacefully.
Lay sees this as evidence that research on more comfortable flooring designs
should help. He plans to test any possible solutions like floor design against
the industry data, to check and adjust for practicality. For example, any new
floor design has to consider pig rooting behavioranything they can get
their nose under they can destroy.
The causes of piglet crushing are a big unknown. There are few answers and many
Lay is focusing on why sows don't seem to hear their piglets' piercing squeals
as they lie on them. Are the sows confused because they hear other piglets
squealing from other nearby litters? Or are these sows genetically programmed
to be insensitive?
It may be a little of both; Lay has seen sows who are very alert to the cries
of both their litters and others.
Modern methods of raising sow families indoors in close proximity to other
families could be part of the problem, according to observations and research.
Not only do animals like to be alone when giving birth, but also the cries of
other litters may desensitize sows to cries of their own piglets.
One thing Lay noticed is that the piglets, nearsighted and awkward as they are
at birth, can find their mother's udder within minutes after birth. Julie
Morrow-Tesch's experiments with piglets in a maze showed that it was the
mother's milk scent on the udder that guided the piglets.
Lay tried to figure out what it would take to entice piglets away from their
motherand the crushing danger. He noticed the piglets ignored the warmth
of a heat lamp and preferred mother's warmth and milk during the first critical
24 hours of life.
So Lay designed artificial udders and covered them with cloths that had the
scent of the mother's udder on them. The artificial udders worked, but
large-scale tests are needed to see if they decrease crushing deaths.
Living quarters are an important factor in piglet mortality. Currently used
farrowing crates save lives, compared to pens. The crates are designed to hold
a sow during the weaning process and keep her from rolling on her pigs by
forcing her to lie only straight down. In Europe, some operations use farrowing
crates with a 1-foot curb barrier that allows the sow to come and go freely,
whereas the piglets can't leave until they can climb the barrier, usually in a
week or two.
Jeffrey Carroll's work on cold stress showed that when piglets are chilled
below their desired 85 °F, they become more vulnerable to respiratory and
Lay has found that chilled piglets are prone not only to disease, but also to
being crushed. This is because the piglets spend more time very close to Mom to
keep warm. They're also weaker and less likely to move away from danger
Runts of the litter are also more susceptible to suffocation, because they are
smaller, weaker, and more likely to become chilled.
Lay presented his findings on piglet mortality at this year's joint Midwest
section meeting of the American Society of Animal Science and the American
Dairy Science Association in Des Moines, Iowa.
Lewis W. Smith
ARS National Program Leader