Effects of live animal handling on carcass and meat quality
12 important questions on Effects of live animal handling on carcass and meat quality
What can you tell about live animal handling
- Animal loading & unloading can be difficult & stressful
- Some vehicles require steep loading ramps = difficult for animals to negotiate
- Pigs are more easily loaded & unloaded using vehicle tailboard hoists or tail lifts
- Poultry harvesting: catching birds & placing in transport crates
- desirable to prevent physical damage
How can transport time affect meat quality?
- Animals can spend considerable times in transit
- On arrival at plant animals held for various lengths of time before slaughter in a large or stockyard
- Need to be supplied with water & (if appropriate) bedding & food
- Lairage conditions should be conducive to animal resting - recover from rigours of transport
- Animals can spend between 1 & 24 hours in lairage
- Most commonly recognised consequence of poor pre-slaughter handling on lean meat quality = PSE meat in pigs & DFD meat in pigs & cattle
- Total loss = animal dies during transport
Even when carried out with car & consideration marketing process are inherently stressful to animals. It involves ... And results in ...
- Removal from home environment
- Loading & unloading on to vehicles
- Often long journeys
- Holding in unfamiliar surroundings with different animals
Result in potential exposure to physical stress
- Extremes of temperature
- Vibrations & noise
- Changes in acceleration
- Close confinement
- Crowding
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Which two major factors influence incidence
- Environmental temperature
- <10*C very low incidence
- >18*C rapid increase in mortality
- Leads to well-defined seasonal effect - most deaths during hottest months
- Pigs reared in hotter countries appear somewhat tolerant to higher temperatures
- Genotype
- Stress-susceptible breed of pigs more prone to dying in transport
- Largely explains variation between countries - many more pigs dying in places where genes from stress-susceptible breeds are widely disseminated
- Even in countries where frequency Halothane gene low - effect on mortality in transport can be demonstrated
Why is carcass damage a problem?
- Bruising can occur at any point in marketing chain
- Bruise - blood from damaged blood vessels, accumulate in surrounding tissue
- bruised meat looks unsightly & usually trimmed
- regrading quality, red meat species bruising = aesthetic rather than a hygiene problem
Factors which increase bruising in cattle
- Long periods without food
- Chronic stress
- Transport
bruises can very both in number & severity or size
Various methods for assessing bruising
- Scoring systems
- Attempts to estimate age of bruises not been very successful
- Characteristic colour changes caused by breakdown of haemoglobin in blood --> bilirubin (yellowish) --> biliverdin (green) = fairly insensitive indices of bruise age
- More sensitive methods to estimate bruise age based on measurement of concentration of bilirubin or histological changes (but much more expensive)
How can skin blemishes on pig carcasses be prevented?
- Related problem = superficial skin damage caused by fighting in pigs particularly between unfamiliar animals
- Unsighlty lacerations & detracts from appearance of rind-on products
- when elected for slaughter, pigs from different rearing pens mixed tighter to make up batches with similar live weights
- Disrupts established hierarchies & individuals often fight to establish new dominance orders
- Fighting can be severe & leads to lacerations on skin, particularly on shoulders & lesser extent on loins & hams
What are factors influencing level of bruising [poultry]
- Strain of bird
- Season
- Degree of muscling
- Care during handling
PSE & DFD are two major quality problems facing meat industry, namely
- PSE mainly affects pigs
- DFD occurs in all species
- PSE like characteristics been reported in turkey & chicken
- PSE also found in M. Longissimus dorsi of beef (prevalence very low)
What are the pH values of PSE & DFD meat at a specific time (pH45 & pHu)
What are two reasons for the high spoilage potential of DFD meat
- DFD meat caused by glycogen depletion ante-mortem has low levels carbohydrates in muscles
- High pH meat can be problem when vacuum packed
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