Meat Quality

The waveform and frequency of the supply voltage can alter the effect that electric current has on animals. Consequently, electrical stunning is often blamed for meat quality issues leading to carcase downgrading. As a result, adjustments are sometimes made to electrical equipment that could compromise animal welfare.

Most conventional stunners operate with the same 50Hz sine wave as the mains supply (Figure 3b). However, research has demonstrated that direct muscle stimulation is responsible for downgrading conditions. Increasing the frequency of the applied waveform to 1500Hz significantly reduces the level of direct muscle stimulation and manufacturers have now produced equipment which applies high frequency current followe
d by low frequency current. Research has also shown that, although electrical stimulation of muscles at stunning can lead to blood splash, bruising and broken bones, the occurrence of these conditions also depends on other factors, including: the source, breed and strain of the animal; nutrition; changes in tempe

rature prior to slaughter; pre-slaughter handling; and interrupted contact of stunning electrodes. These may account for the frequency and random nature of the incidence of downgrading between individual animals. All these factors must be thoroughly investigated before making changes to the settings of a stunner.

Any changes to stunner settings which could compromise animal welfare must not be made in an attempt to rectify meat quality problems.