Helping Piglets Survive and Thrive
Animal physiologist Robert Matteri examines the growth of bacterial cultures
containing cloned DNA of genes for appetite control.
Getting newborn piglets off to a good start in life is no easy task, even
though raising hogs is among the most technologically advanced of animal
industries. Of every 10 pigs born alive, at least 1 doesn't survive more than a
few days. Those losses alone reduce swine producers' net income by several
hundred million dollars a year.
Some piglets handle stress poorly, are prone to disease, weigh less than
their siblings at weaning, and require an additional week or longer of care and
feeding before going to market. Faster growth would lower housing, feeding, and
"Reducing the average time from birth to market by just 1 day could
translate into an annual income boost of tens of millions of dollars for the
nation's swine producers," says ARS
animal physiologist Robert L. Matteri. He's based in the ARS Animal Physiology
Research Unit, at Columbia, Missouri.
Matteri's team of three ARS scientists along with their University of
Missouri colleagues are researching piglets' susceptibility to death, disease,
stress, and poor growth. "Our goal is to find ways to improve their
well-being and to optimize cost-efficient growth," says Matteri. Pigs that
grow well when quite young generally gain more weight per pound of feed
consumed after weaning and have less carcass fat when they reach market weight.
You Can Lead a Pig to Food . . .
A major limitation to improved neonatal growth is poor feed intake. That's
why the scientists are looking at a variety of hormones involved in appetite
control. The researchers must conduct extensive physiological research before
they can develop practical farm procedures for using hormones like
neuropeptide-Y, leptin, and orexins in the forms of orexin-A and orexin-B.
Matteri and ARS animal physiologist Cheryl J. Dyer became interested in
orexin after University of Texas scientists saw a sixfold increase in feed
intake in rats given brain injections of the hormone. The researchers in
Missouri then found that a single injection in the upper hind leg muscles of
3-week-old pigs increased feed intake 18 percent, though for only a short time.
These initial findings earned the National Pork Producers Council's
innovation award for basic research earlier this year at the Midwest Animal
Sciences meeting in Des Moines, Iowa. More research should show whether two or
more well-timed injections can help improve growth rates enough to be
Animal physiologist Jeff Carroll analyzes swine tissue to determine the
presence of stress-responsive hormones.
Dyer and Matteri cloned the orexin molecule chemically. When analogs, which
are smaller but potent synthetic versions, of orexin are designed and
mass-produced, Dyer says, the cost of injections should become fairly
If treatments with hormones such as orexin could help all littermates grow
at nearly the same pace, meat packers discounts of $0.50 to $2.50 per
hundredweight on lightweight hogs could be avoided. And if all hogs could be
marketed together, farmers could take better advantage of an "all-in,
all-out" inventory management system that helps break disease cycles. This
systemmarketing all animals at the same timeallows producers to
completely empty housing for thorough, periodic sanitation.
The scientists are researching another way to deliver orexin. They have
cloned the genetic material, or DNA, that directs orexin production and have
integrated it into another piece of DNA called a mammalian expression vector.
The next step: injecting the new DNA, a so-called designer gene, into the
animals' own cells to see if they will produce larger amounts of biologically
The research on appetite regulation being conducted at Columbia complements
ongoing work at other ARS laboratories. ARS researchers at Athens, Georgia, and
Beltsville, Maryland, are studying the biology of leptin, a hormone that also
controls appetite. The goal of these coordinated, and often collaborative, ARS
research efforts is a working understanding of the biological control of feed
intake as it relates to animal production, health, and well-being.
Birth and Other Stresses
Besides affecting appetite, hormonesin complex waysexert major
impact on swine health in production environments. There, for better or worse,
stress is encounteredespecially at birthas pigs are weaned,
handled, and moved about. In researching hormones that indicate stress, ARS
animal physiologist Jeffery A. Carroll and his colleagues in Columbia have
found that stress during birth may play an important role in preparing a fetus
for life beyond the womb.
In the experiments, some young pigs were born naturally while others came
into the world via cesarian section. At birth, blood and tissue samples from
the two groups contained some similar but other strikingly different hormone
and chemical levels. Two weeks later, more similarities and differences
appeared, giving insights on lasting effects of birth experiences. The
researchers concluded that by preventing the stress of natural birth, surgical
birth inhibited the pigs' growth.
Animal physiologist Cheryl Dyer observes healthy, 10-day-old piglets.
Diet may also have an important link with stress. Carroll has just begun
researching the effects of new protein supplements like spray-dried plasma on
the secretion of stress-related hormones after animals are confronted with real
or simulated disease. This research is aimed at identifying and controlling
responses to stress.
In a multifaceted study of newborn piglets' general ability to develop
resistance to diseases, Carroll and Matteri have been exploring the effects of
environmental temperature. The research has shown that the piglets, lacking the
ability to develop an acute fever, actually become hypothermicthat is,
lose body temperatureduring a disease challenge. Chilling may, and often
does, lead to death.
The scientists treated piglets with an anti-inflammatory drug similar to
aspirin and ibuprofen before injecting them with a lipopolysaccharide from
killed bacteria to simulate infection by a live disease organism. The drug
prevented hypothermia. More important, by observing chilling and changes in
body chemistry in pigs with and without the drug, the scientists are now on the
way to finding ways to improve growth and reduce sickness and death among young
pigs.By Ben Hardin,
Agricultural Research Service Information Staff.
This research is part of Animal Well-Being and Stress Control Systems, an
ARS National Program described on the World Wide Web at
Robert L. Matteri,
Jeffery A. Carroll, and
Cheryl J. Dyer are in the
Physiology Research Unit, 920 E. Campus Dr., University of Missouri,
Columbia, MO 65211; phone (573) 882-1047, fax (573) 884-4798.
"Helping Piglets Survive and Thrive" was published in the
September 1999 issue of
Agricultural Research magazine.