Stunning Cattle with Electric Current: Methods, Voltage and Equipment

Cattle slaughtering plants use three schemes for stunning cattle with electric current, distinguished by how the electrical contacts are applied to the animal's body (Fig. 1): Figure 1 - Stunning with electric current

The three electrical stunning schemes for cattle differ in contact placement and grounding:

• Under the VNIIMP scheme, two contacts are applied to the occipital (back) part of the animal's head. This method produces few fatal cases, but the animals' limbs contract convulsively, which is inconvenient and dangerous for workers;
• Under the Baku Meat Plant scheme, one contact is a sharp rod mounted in a goad and applied to the occipital part of the animal's head. The second contact is a metal plate on which the animal stands with its front legs; its hind legs rest on an insulating rubber plate;
• Under the Moscow Meat Plant scheme, the stunning electrodes are mutually insulated plates mounted in the floor of the box and supplied with three-phase current. One phase is connected to the first and fourth plates, the second to the second and fifth, and the third to the third and sixth plates. Once the animal is positioned in the box, electric current is supplied to the contacts.

A herd of cows in a pasture

In all three schemes the frequency of the electric current is 50 Hz. The voltage of the current and the duration of stunning for cattle depend on the animal's age, as shown below:

The action of electric current can sometimes cause convulsive muscle contraction and fracture of the spine, along with haemorrhage in the animal's tissues and organs. To prevent such cases, a new stunning device for cattle has been developed. The device delivers an output voltage of 300 V, a current of 2 A, and a frequency of 50 Hz, with the exposure time reduced to just 2–5 seconds depending on the animal's weight.

Stunning animals with this device reduces the number of fractures and haemorrhages by a factor of 2.6 compared with the devices currently in use. Electric current stunning is carried out in boxes of various designs, with automatic and universal continuous-action boxes having become widespread.

What is the FEOR-1 apparatus and how does it work?

The FEOR-1 apparatus is designed for stunning cattle at meat-processing plants of all types and at slaughter points equipped with boxes. Stunning is performed by passing an alternating current with a frequency of 50 Hz through the animal, with the electrode applied to the head while the animal is grounded through its front legs.

Using the FEOR-1 apparatus ensures the safety of the personnel who hoist the animals onto the bleeding line. The apparatus (Fig. 2) consists of a control station, limit switches installed in the box, and a goad with a spear fixed at its end.

The control station consists of a metal cabinet with a hinged front cover, inside which a transformer, fuses, and relays are mounted. On the cabinet cover are a packet switch, a panel selector switch, an ammeter, a voltmeter, and signal lamps. At the bottom, the cabinet has three sockets: for supplying voltage to the apparatus, for the box floor, and for the goad's supply cable. Brackets are welded to the rear wall of the cabinet for fastening the apparatus to the wall. Figure 2 - FEOR-1 apparatus for electrical stunning of cattle: 1 – control station; 2 – goad; 3 – spear; 4 – limit switch.

The goad is an insulating tube with a stainless-steel spear at one end and a fitting for connecting the supply cable with a plug at the other. A switch with a lever is built into the tube.

Two limit switches are installed along the line from the apparatus to the floor and the door of the box; they break the goad's supply circuit when the side wall of the box is raised. The electrical cable is laid in tubes. During stunning, the end of the goad is used to puncture the animal's head while simultaneously pressing the lever of the switch on the goad. At this moment the signal lamp should light up.

The current and voltage values are determined according to the applicable instructions for the slaughter of cattle and the dressing of carcasses.

How does mechanical stunning of cattle work?

Mechanical stunning consists of striking the frontal part of the animal's head with sufficient force using a wooden (or metal) mallet, a pneumatic hammer, or a captive-bolt device (pistol), without breaking the integrity of the bones.

With mechanical stunning, fractures of the skeletal bones and haemorrhages in the tissues and internal organs are avoided. As a result, the quality of the meat is better than that of meat obtained from an animal stunned with electric current.

At the same time, this method is more labour-intensive and requires higher operator skill. Stunned animals are unloaded onto the floor. To hoist them onto the bleeding line, one or both hind legs of the animal are wrapped around the cannon-bone area with a shackle chain and hook; the resulting loop is tightened, and the roller of the shackle chain is hooked onto the hook of the loading machine.