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Studies on Pre-slaughter Handling of Pigs and its Relationship to Meat Quality
Lynch, P Brendan Lawlor, Peadar G Davis, D. Kerry, Joseph P. Buckley, D.J. Walsh, L.
Lynch, P Brendan
Lawlor, Peadar G
Davis, D.
Kerry, Joseph P.
Buckley, D.J.
Walsh, L.
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1998-12-01
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Lynch, P.B., et al., Studies on Pre-slaughter Handling of Pigs and its Relationship to Meat Quality, End of Project Reports, Teagasc, 1998.
Abstract
Two quality defects of pork which are affected by preslaughter
handling are PSE (Pale Soft Exudative) and DFD (Dark
Firm Dry) meat.
The incidence of PSE pork is mainly a function of the breed of
pig but short-term stressful handling before slaughter and feeding
too close to slaughter are also involved. DFD meat is a result of
prolonged stressful handling. PSE meat is pale and uneven in
colour and exudes fluid making it unattractive in the retail display
while dark meat appears stale and is prone to bacterial spoilage.
After slaughter muscle metabolism continues and muscle glycogen
is converted to lactic acid reducing meat pH. Prolonged stress
results in glycogen depletion, pre-slaughter feeding results in
elevated levels. Colour may be assessed subjectively by eye or
objectively by a meter colour but pH of the meat is closely related
to colour and measurement of pH at 45 minutes post-slaughter is
frequently used to predict ultimate colour and pH.
The objective of this study was to examine pre-slaughter handling
practices and their relationship with meat quality (pH, colour).
In the first trial, a survey of the amounts of stomach contents in
pigs at slaughter in two factories found similar amounts to
comparable surveys in France and the UK. It was concluded that
most pigs had been fasted for an adequate time before delivery.
The relationship between the amount of stomach contents and
meat quality in this survey was poor.
In the second trial, pigs from the Moorepark herd fed by either a
computerised wet feeding system or an ad libitum dry feed system
were slaughtered after overnight fasting or with feed available up
to loading for transport to the factory, two to three hours before
slaughter. There was no difference between feeding systems in
meat colour or pH but fasted pigs, on both feeding systems, had
darker meat and meat of a higher pH.
In the third and fourth trials a survey of transport vehicles was
carried out and meat quality of pigs delivered in modern and old-type vehicles was compared. Most trucks examined (78%) were
four years old or more. Few had modern hydraulic lifting gear for
the top decks. Space allowances during transportation were
generally adequate but delays in unloading could, in warm weather,
cause stress on pigs. There was little evidence for an effect of
vehicle on meat quality parameters but day to day variation in
carcass temperature and pH suggested a need for further research
on factory influences on meat quality.
Feeding of Magneium Aspartate to pigs for the last 5 days prior
to slaughter has been shown, in Australia, to have a beneficial
effect on meat colour and drip loss. In the final trial in this study
Mg Asp had no effect on meat quality parameters.