Two quality defects of pork which are affected by preslaughterhandling are PSE (Pale Soft Exudative) and DFD (DarkFirm Dry) meat.The incidence of PSE pork is mainly a function of the breed ofpig but short-term stressful handling before slaughter and feedingtoo close to slaughter are also involved. DFD meat is a result ofprolonged stressful handling. PSE meat is pale and uneven incolour and exudes fluid making it unattractive in the retail displaywhile dark meat appears stale and is prone to bacterial spoilage.After slaughter muscle metabolism continues and muscle glycogenis converted to lactic acid reducing meat pH. Prolonged stressresults in glycogen depletion, pre-slaughter feeding results inelevated levels. Colour may be assessed subjectively by eye orobjectively by a meter colour but pH of the meat is closely relatedto colour and measurement of pH at 45 minutes post-slaughter isfrequently used to predict ultimate colour and pH.The objective of this study was to examine pre-slaughter handlingpractices and their relationship with meat quality (pH, colour).In the first trial, a survey of the amounts of stomach contents inpigs at slaughter in two factories found similar amounts tocomparable surveys in France and the UK. It was concluded thatmost pigs had been fasted for an adequate time before delivery.The relationship between the amount of stomach contents andmeat quality in this survey was poor.In the second trial, pigs from the Moorepark herd fed by either acomputerised wet feeding system or an ad libitum dry feed systemwere slaughtered after overnight fasting or with feed available upto loading for transport to the factory, two to three hours beforeslaughter. There was no difference between feeding systems inmeat colour or pH but fasted pigs, on both feeding systems, haddarker meat and meat of a higher pH.In the third and fourth trials a survey of transport vehicles wascarried out and meat quality of pigs delivered in modern and old-type vehicles was compared. Most trucks examined (78%) werefour years old or more. Few had modern hydraulic lifting gear forthe top decks. Space allowances during transportation weregenerally adequate but delays in unloading could, in warm weather,cause stress on pigs. There was little evidence for an effect ofvehicle on meat quality parameters but day to day variation incarcass temperature and pH suggested a need for further researchon factory influences on meat quality.Feeding of Magneium Aspartate to pigs for the last 5 days priorto slaughter has been shown, in Australia, to have a beneficialeffect on meat colour and drip loss. In the final trial in this studyMg Asp had no effect on meat quality parameters.
AGRIP End of Project Reports
Teagasc End-of-Project Reports