A proper environment makes a big bottom-line difference
In the harsh atmosphere of a slaughtering plant, perhaps no job is more important than stunning cattle as they enter the slaughtering area.
Mistakes in lighting, ventilation, or failure to reduce high-pitched noises will impede the orderly movement of cattle, according to Temple Grandin, assistant professor of animal science at Colorado State University. It is a matter of economics for packers and processors.
If an animal is not properly relaxed during the stunning cycle, the result could be lower prices for meat because of color deterioration.
Grandin examined 18 meat plants-including 12 beef plants-to ascertain the reasons why animals hesitate and refuse to enter a stunning box or conveyor restrainer. The beef plants, some modern and some older, slaughtered between 30 and 275 head an hour The restrainers and boxes were designed correctly in all plants, but changes needed to be made in lighting, noise reduction and ventilation air flow patterns to improve animal movement.
Lighting
Grandin points out that animals must be able to see where they are going; in very few instances will animals enter any area that is dark. In two beef plants, lamps aimed at the restrainer entrance were used to attract the cattle.
But Grandin cautions that the lamps must be aimed away from approaching animals so that they illuminate the restrainer entrance.
If the light is shined into the eyes of the oncoming animals, it will impede their movement into the restrainer. Animals will not approach a blinding light shining directly into their eyes.
In two beef plants, the handling system and restrainer worked successfully when lamps in the room were new, Grandin says. Balking and refusal to enter the conveyer restrainer progressively worsened as the sodium lamp bulbs dimmed with usage. When the bulbs dimmed, the animals could no longer see into the restrainer entrance.
Cattle need to see where they are going as they enter a conveyor restrainer or stunning box, according to Grandin.
She adds, however, that the light must be blocked underneath the conveyor restrainer to prevent the animals from seeing the steep drop-off under the conveyor. The installation of a "false floor" underneath the restrainer will improve animal movement onto the conveyor.
Observing movement
If employees are moving about, cattle will sense it and might refuse to enter the stunning area, says the manager of a beef packer's slaughtering floor. This is also true if the animals see reflections off water or a moving object ahead of them. In one plant, cattle refused to enter a single-file race because they saw a small hanging chain that wiggled. In two other beef plants, cattle saw reflections off standing water on the floor, which impeded their movement.
In another case, cattle refused to enter the stunning area because they saw a moving sparkling reflection on a metal partition.
In two beef plants, installation of shields to prevent approaching animals from seeing moving people ahead facilitated cattle movement, Grandin notes. Adjusting the angle of a light usually eliminates reflections.
Noise reduction
The hearing of livestock are more sensitive than human hearing. This means that high-frequency noises and the banging of metal will cause animals to hesitate and refuse to move, and intermittent hissing noises from air valves will cause an animal to be startled, Grandin stresses.
Undersized pipes in a hydraulic system in one beef plant created a high-frequency sound that caused cattle to hesitate and refuse to enter a restrainer.
Enlarging the pipes eliminated the high-frequency sound and made it easier to get the cattle into the restrainer. Enlarging the diameter of the pipes reduces high-frequency sound because hydraulic fluid moving through a large pipe moves at a slower speed. Grandin points out that objects in many plants agitate animals; Conversely, cattle voluntarily enter equipment that makes low-frequency sounds.
Ventilation
Poor ventilation will sabotage the best of systems, a manager of a slaughter area says. Smells that blow back in the face of animals can cause them to hesitate entering the restrainer.
Cattle movement in several plants improved by designing a ventilation system that created a zone of negative pressure at the stunning box or entrance to the restrainer conveyor, taking the smell away from the waiting animals.
In one plant, the ventilation system blew the aroma of the slaughterhouse at the animals. At another plant, cattle moved freely into the stunning boxes when the wind was coming from one direction, but balked when the wind was coming from another direction.
An odor causes animals to stop when they first smell it, according to Grandin. If animals are first exposed to slaughtering smells in the lairage, they appear to gravitate toward them and they will usually walk up the races.
Smells cause the worst impediments to animal movement if they first encounter the smell at a stunning box or restrainer entrance. The smell of a slaughter hall odor in the lairage may impede movement in the lairage, but the animals will usually walk into the stunning box or restrainer.