Transport duration effects on MSA eating quality

Summary

The Meat standards Australia Australia (MSA) grading model uses multiple inputs to predict the eating quality of individual cuts of beef.  In addition to these inputs MSA uses several threshold or exclusion traits aimed at minimizing animal stress and poor quality meat.  
Cattle presented for MSA grading cannot be mixed immediately prior to slaughter, must be slaughtered the day after dispatch and have water available up until slaughter. At slaughter the exclusions include carcasses with ribfat < 3mm, ultimate pH > 5.7 and meat colour scores >3.
The minimum ribfat measurement was designed to provide buffering against extreme cooling rates in areas of the carcass with little or no fat covering. Exclusion of high ultimate pH and carcasses with dark meat colour provided some insurance against tougher meat and also dark meat at retail. Most cattle in Australia are trucked less than 12h to slaughter, although much of the extensive northern pastoral region requires longer periods to transport cattle to slaughter.  
Whilst it is theoretically possible to transport cattle up to 48h before slaughter and still be eligible for MSA under theday after dispatch standard this would exceed the 36h maximumwater deprivation time recommended for cattle in Australia. When practical considerations (ie loading during daylight, abattoir operating times, AQIS regulations and the general industry practice of up to 12 hours in lairage at the abattoir prior to slaughter) are taken into account, the maximum transport duration would be between 24 and 36h, followed by up to 12h rest during lairage where cattle have access to water.
The experiment was designed to test the effect of four cattle transport treatments on sensory and objective measurements of meat quality. In addition blood and urine, measurements were examined as predictors of eating quality. The experiment utilised a total of 343 cattle in a replicated design with four trucking treatments.  The four replicates were undertaken on four different properties in central Queensland.
This experiment found no treatment difference in eating quality, live animal, carcass, blood, urine or objective traits for four transport times ranging from 12 to 36 hours from property to the abattoir with slaughter following overnight lairage. The one exception was a small increase in blood glucose concentration in the treatment transported for 24 hours.While there were large and concerning individual animal differences in ultimate pH and meat colour these were not aligned with treatment.