| Working with colleagues at the
University of Florida-Gainesville, Eicher found that mixing formula-treated
beef calves with those from other herds wasn't nearly as stressful as
weaning and transporting. As indicators, they used behaviors and blood
levels of cortisol, liver proteins and other proteins, and immune system
indicators like IgG.
Eicher is also finding that acquainting young, pregnant cows with milking
parlors and milking before their first births reduces stress when they're
milked after their calves are weaned. She completed two studies with
cows in Purdue's herd of 200 confined dairy cattle. She also worked
with colleagues at Mississippi State University who did a similar experiment
with a grazing herd.
According to Eicher, "There was lowered stressas measured
by increased milk production, less nervous weight shifting in milking
stalls, and a quicker return to normal levels of heptaglobin, a protein
that cleans up hemoglobin after tissue damage or other stressesin
the cows in all three experiments. But the benefits were clearer in
the confined herd."
The Last Thing Over the Fence
Eicher has been working with Cheng for the past 8 years to see whether
removing dairy cows' tails by constrictive banding causes them chronic
pain. She is the first U.S. researcher to study the practice, called
"tail docking." It's commonly done by dairy farmers for sanitary
reasons and is growing in popularity, moving from adults to calves at
Eicher and Cheng have found both behavioral and physiological signs
indicating that animals may suffer chronic pain from tail docking. Not
only do calves pay attention to the stump, they also show physiological
and neurological signs usually associated with "phantom limb"
pain in people. The data showed that young calves actually respond to
the pain more than adult cows do, a finding that doesn't support the
normal practice of conducting painful procedures on young animals rather
than older ones. Researchers observed an increase in blood temperature
in the area around the tail and formation of neuromasbundles of
nerves occurring at their damaged endswhich can transmit pain
spontaneously. The fact that Eicher's behavioral observations match
up with Cheng's discovery of neuromas makes a stronger case for the
likelihood of chronic pain.
Cheng uses a careful procedure to search for neuromas and other possible
nerve damage that could cause chronic pain or hypersensitivity to temperature
or touch. This includes an elaborate procedure for staining nerve tissue
for electron microscopy study.
The First Thing Into the Feed Bin
Cheng also looks at neuromas to evaluate a similar practice in poultry
production: beak-trimming. Farmers trim from a third to a half of the
beaks off chickens, turkeys, and ducks to cut losses from poultry pecking
"Poultry beaks are much more complex structures than cattle tails,"
Cheng says. "They're really intricate, so it's not hard to cause
problems when cutting them. Sometimes the beaks are deformed as they
heal, which interferes with eating or other instinctive behaviors, like
Cheng is tackling that problem from two angles: finding the most humane
way to trim beaks and eliminating the need to trim them. He's first
looking at infrared and laser techniques as alternatives to the knives
currently used. He recently completed a study with Pajor on trimming
the beaks of Muscovy and Pekin ducks. That data is currently being analyzed.
But Cheng thinks the need for trimming can be eliminated by breeding
gentler poultry, so he's found a breeding line of such chickens. He
and his colleague, Bill Muir, a professor at Purdue University, believe
that breeders of many types of livestock have inadvertently bred more
aggressive animalswith less maternal instinct and ability to cope
with stressas they've selected for traits such as productivity.
USDA recognized the significance of their findings on the ability to
reduce aggression through genetic selection by awarding them an NRI
grant of $300,000 to continue their work.
A House Is Not a Home
Eicher and Pajor found that piglets born to sows housed individually
in conventional stalls bore evidence of the stress the housing caused
their mothers. Piglets from stall-housed mothers had lower growth rates
and increased measures of stressincluding more squealingduring
an isolation test after weaning than piglets from group-housed sows.
Jeremy Marchant-Forde also works with Eicher and Pajor on alternative
housing for sows.
Confining pregnant sows in stalls is a major well-being issue. It curtails
movement and social interaction and fails to provide dirt or hay to
satisfy their instincts to use their snouts to root for food.
So Pajor is asking sows what they prefer. He's set up a way to let
them choose either extra food or space and company. Each sow is in a
typical gestation stall, but she is able to push a bar to open a door
that lets her visit the sow on either side of her stall. Or she can
push another bar and get a little extra food. The scientists rate a
sow's motivation or priority level by the number of times she's willing
to press a bar to get her reward.
To his surprise, so far the sows are choosing extra food. His first
project was done with 16 sows, studying 4 at a time from Purdue's herd
of 250 sows.
"Scientists have often compared sows in different housing situations,"
says Pajor. "What's new here is letting them choose the 'extras'
to see what their priorities are.
The current setup is a typical, barren environment, with slatted cement
floors. The next round of experiments will see whether the sow chooses
different options in an enriched environmentwhere there's more
to do, a soft floor, and straw to satisfy instincts like nesting or
Getting Along With Others
Lay is also working with Pajor on experiments to show the effects of
an enriched environment on baby pigs, including the socializing effects
of letting young from different litters play and interact at about 10
days of age.
"We want to see whether there is an age window for socialization,"
Pajor says. "Could early socialization help piglets cope better
when mixed with different pigs later in life? Could it help them spot
dominant pigs and get in fewer fights, for example? That would be good
for both the pigs and the farmers.
"When a lot of these indicatorsbehavioral and physiologicalcome
together and point to the same thing, you begin to feel that you've
proven the animal is experiencing stress," Pajor says. That has
already happened in several cases as ARS farm animal stress research
begins its second decade, fulfilling its mandate to seek out objective
measures of stress and ways to alleviate it.By Don
Comis, Agricultural Research Service Information Staff.
This research is part of Animal Well-Being and Stress-Control Systems,
an ARS National Program (#105) described on the World Wide Web at www.nps.ars.usda.gov.
To reach scientists mentioned in this article, contact Don
Comis, USDA-ARS Information
Staff, 5601 Sunnyside Ave., Beltsville, MD 20705-5129; phone (301)
504-1625, fax (301) 504-1486.
"Settling Doubts About Livestock Stress" was published
in the March
2005 issue of Agricultural Research magazine.