How pre-slaughter stress impacts meat quality
Find out how a high level of stress in the last couple of days prior to slaughter can impact red meat quality.
Areas to reduce stress
Novel experiences can be stressful to animals on an individual basis, so it is important to be mindful of their welfare. This is also true when considering the lead up to slaughter as a lower standard of welfare may also result in lower meat quality.
- When sorting animals for transportation or at markets, it is important to minimise the mixing of unknown groups
- If mixing is necessary for transportation, make sure animals are not kept in these groups for extended periods of time, i.e. 1–2 days prior to slaughter
Transportation and vehicles
- Always use the correct vehicles for the species you are moving
- Ensure that ramps on and off the vehicles are suitable and meet regulations
- Follow regulations around stocking densities and journey times
- The time spent in the lairage is crucial, particularly when considering bulls (which should be moved directly from transport to slaughter)
- Be aware that sheep often feel less stressed when they can see other sheep around them. However, cattle can become more distressed. Think about how the lairage pens are designed for the species
- Keep pigs in known groups until the point of slaughter
- Make sure that there are no pools of light or dark areas which will prevent the animals from moving easily through the raceways
- Ensure that temperatures and ventilation are optimal to reduce stress to pigs (cattle and sheep are less susceptible to heat stress)
- Use the animals’ natural behaviours to move them on and off transport as well as through the lairage
- Try to avoid contact with the animal as this can cause increased stress levels. Instead, use flags as an extension of your arm to encourage movement
Muscle to meat conversion
Understanding how live muscle converts to meat is important to be able to maximise meat quality.
Meat quality defects caused by stress
During the natural conversion of muscle to meat, the pH will fall from around 7 to 5.4–5.7. When an animal has experienced a period of chronic stress (typically 24–48 hours before slaughter), the pH does not fall to the optimum level and stays higher, resulting in meat which is compromised.
A higher pH will cause the meat to appear darker in colour, firmer to touch and hold fluid within it. For this reason, it is referred to as dark, firm and dry (DFD), also known as dark cutting beef (DCB). In addition to its abnormal colour, DFD meat has reduced keeping qualities and is prone to bacterial spoilage. It is thought that there may be an improved tenderness to DFD beef. However, this benefit does not outweigh the negative impacts on both animal welfare and meat quality.
Acute or shorter periods of stress (around 45 minutes pre-slaughter) can cause the pH to drop very quickly following slaughter. This will typically give an optimum ultimate pH but will have implications on the meat quality. A quick pH fall can cause the meat to appear lighter in colour, have a softer texture and feel wet as it has a reduced capacity to hold fluid. This is referred to as pale, soft and exudative (PSE). Whilst this is not commonly seen in lamb, it can be seen in beef and more frequently pork.