Industrial application to cattle of a method for the early determination of meat ultimate pH.

A method to measure the approximate glycolytic potential of slaughter animals, and thus the ultimate pH, was applied for several months on the slaughter line of a cattle abattoir. The patented method (WO 00112844) determines a so-called glucose value from the hydrolysis of glycogen in a sample of Longissimus lumborum. The value is available before the dressed carcass is weighed and graded. The 13,700 cattle tested were pasture-fed bulls and 'prime' animals, the latter comprising steers and virgin females. The method was used to sort carcasses into two quality grades, table cuts and manufacturing, according to a threshold glucose value that in this application corresponded to an ultimate pH of 5.70. In frequency distributions the glucose value was roughly normally distributed for prime animals but for bulls was lower on average and strongly skewed to low values. The distributions showed that 19% of prime and 62% of bulls had an ultimate pH below 5.70. The results were consistent with prior survey work undertaken in New Zealand with conventional pH measurements made a day after slaughter. Error in the method is examined with respect to commercial outcomes. For most errors the method 'fails-safe', in that normal pH animals are more likely to be classed as high pH than vice versa. In a second phase of the study, meteorological and some abattoir data are related to mean daily glucose values and their variance. The more bulls slaughtered per day the lower the mean glucose value for bulls (r=-0.25, P<0.01), an effect presumably arising from mixing unfamiliar groups of bulls. There was a decrease in mean glucose value with higher maximum daily temperature (P<0.01). Periods of rainfall in the days leading to slaughter were positive for glucose value. For both bulls (especially) and prime, the lower the mean glucose value, the greater the percent variance (r=-0.81 and -0.56, P<0.001) but the cause of this could not be established.