Meat + Poultry - June 2004 - 62

Stunning precision

oncern about bovine spongiform encephalopathy has
sparked a renewed interest in non-penetrating, mushroom-head captive bolt stunning of cattle. A recent report
from the European Commission stated that non-penetrating captive bolt would reduce incidences of carcass contamination with
at-risk brain material.
Effective stunning, which will ensure good animal welfare by inducing instant insensibility, requires sufficient concussive force. Sufficient force damages both the skull and the brain. Reducing the
spread of at-risk materials requires a reduction in the damage to the
head. These two goals are opposites. Minimizing damage to the skull
requires the placement of the shot to be more precise. It must be in
the center of the forehead and be perfectly straight. If the shot is on a
slight angle the animal will remain sensible.
Non-penetrating mushroom-head stunners can be designed to inflict differing amounts of damage to the head. I have observed that
the most effective stunners inflict severe fracturing of the skull. In an
Australian plant I observed a stunner that made a ¾-inch deep fracture in the skull of cattle. Each animal was held in a head holding device and the plant was very effective in stunning.
I had the opportunity to observe another non-penetrating stunner
that was designed to cause less fracturing of the skull. The mushroom head was on high bolt velocity but its travel was restricted. In
87 percent of fed feedlot cattle, it created a 3/8-inch deep fracture.
The skin on the forehead was broken on only 11 percent of the cattle.
There was no visible brain matter on either the animal's forehead or
on the heads after skinning.
The bad news is five fed cattle out of 75 observed showed immediate signs of returning to sensibility even though they were all shot
in the middle of the forehead. Two of the stunning failures were shot
on a slight angle and one was slightly off the center of the imaginary
"X" in the middle of the forehead.

By Dr. Temple Grandin
meatpoultry@sosland.com

The mushroom-head stunner failed completely on one large
steer, which had a heavy bull-like head. After he was shot perfectly
he remained completely sensible and bellowed. The stunner had
no effect on him. A penetrating captive bolt put him down with one
shot, however. In some cases, skull thickness is an important factor.
On 70 out of 75 of the fed cattle I observed (93 percent) the stunner
worked perfectly and the animals became instantly insensible.
I have concluded that when it comes to using non-penetrating
stunners, there is no margin for error. When the stunner is placed
correctly it works and if the targeting is even a little off, it fails.

When it comes to
using non-penetrating
stunners, there is no
margin for error.
It is my opinion that a head-holding device and a chin lift be required to ensure an adequate level of animal welfare when a mushroom-type stunner is used. Mushroom-head stunning must comply
with the standard welfare audit criteria of 95 percent rendered completely insensible with a single shot.
Another possible problem with mushroom-head stunners is the
decreased time frame required between stunning and bleeding. A
short 60-second or less stunning-to-bleeding interval is advised to
prevent animals from returning to sensibility.
I often get asked about the feasibility of using electric stunning in
large U.S. beef plants. It is being used very effectively in New Zealand on grass-fed cattle. The primary problem created with electric
stunners is the occurrence of bloodspots in the meat. The Australians
tried it on feedlot cattle and the blood splash was excessive so they
went back to captive bolt. The problem is fed, feedlot cattle are young
and therefore, their blood vessels are more fragile. Grass-fed cattle
are older and have tougher blood vessels.
M&P
The author operates Grandin Livestock Systems, Inc.,
Fort Collins, Colo., and is an associate professor of animal
science at Colorado State Univ.

A worker uses holds a non-penetrating stunner in Valley Beef's
Australian processing facility located in Grantham, Queensland
(Photo courtesy of Jarvis Products Corp.).

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E-mail the author at: meat&poultry@sosland.com

JUNE 2004

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Meat + Poultry - June 2004

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