Stunning details can make a difference
MEAT&POULTRY, May 1, 2005)
by MEAT&POULTRY Staff
by Dr. Temple Grandin
Equipment can’t be expected to work well, to maintenance issues are ignored. In many plants, I have observed that line speed can be increased without reducing quality, but the line between optimal operation and poor quality narrows.
Performance does not gradually worsen. It often crashes after a critical speed is reached. Often, an employee no longer has enough time to complete a task, becomes overloaded and fails to focus on the details of doing his job correctly.
Changing a few small details in equipment design will often make the task easy again. For example, in one plant, a single stunner operator can only stun 270 cattle per hour, but in another, he can do many more and maintain a good stunning score of 97 percent or better.
The plant with the higher speed made three small changes in its equipment. The changes involved adjusting the angle of a handle on the pneumatic stunner, improving the balancer and providing shorter operators with a platform that was raised three inches.
In some facilities, I have observed that the equipment manufacturer’s maintenance and operating specifications are not followed. Computer-controlled electronic hog stunners can greatly reduce blood splash if they are maintained correctly. Because this stunner is a computer, it must be housed in a climate-controlled room, and it must not be put in a box at the restrainer.
Plants where the stunner does not work correctly, it is often housed in a damp location. I asked one plant manager, "Would you keep your new laptop computer in the restrainer room?" In plants where this stunner really performs well, it is stored in a climate-controlled room, and switches, cords and plugs in the stunning wand are replaced frequently because wear and moisture affect the current.
It is also essential to keep the stunning wand handle, where the switch is located, dry. Wet wires and switches will interfere with precise control of the current.
In another plant, a pneumatic stunner was breaking down frequently. I noticed that it sounded extra loud. I later discovered that the plant was using a slightly undersized compressor, and to maintain the minimum pressure required to stun the cattle the operator had turned the compressor up 20 pounds per square inch over the manufacturer’s recommended setting. By doing this, the undersized compressor was able to maintain the minimum required pressure.
The problem was that the compressor could not provide enough air volume to maintain a continuous amount of air at the correct pressure. The higher setting enabled the undersized compressor to catch up during breaks and lunch. Therefore, the setting was too high about half the time.
Hydraulic pressure adjustment
Another detail often overlooked in hydraulic systems is the need to set different parts of a restraining device at different pressures. For example, a head-holding device requires much less pressure than a heavy door on a stun box. If the door and the head holder work off the same pressurerelief valve, too much pressure can
be applied to the cow’s head. The head holder should have a separate pressure-relief valve set at a lower pressure. Running the door and the head holder off the same relief valve will result in too much pressure being applied to the cow’s head unless the operator is very careful.
A separate relief valve should be set so the pressure applied to the cow’s head will automatically stop at the right pressure. The cow should not vocalize when the control lever is held all the way down, and the pressure-relief valve opens and bypasses hydraulic fluid back to the reservoir.
Dr. Temple Grandin operates Grandin Livestock Systems, Inc., Fort Collins, Colo., and is a faculty member in the animal science department at Colorado State Univ. We would like to hear from you— your comments and questions about this article are welcome.