Factors Hierarchy in the Meat Production Process, to Model pH in Beef Meat

Most bibliography quotes factors related to pH effect on beef meat; generally principal effects or some interactions between them. This research work tried to identify those factors with main effects on beef meat pH, measured at 36 h post mortem and all complex interactions between them. A data base of 1800 complete registers from animals, out seven slaughter plants which altogether explain 50% of the slaughter in Uruguay. With factors measured on the different stages of the process, a decision tree was adjusted, which showed 12 terminal nodes. It was observed that if the slaughter plant did not use electrical stimulation, if the hygiene conditions were good in the holding pens, and the distance between them and the stunning box was short, the incidence of pH >= 5.8 in meat was low. The lack of hygiene in pens affected more pure British breeds (Hereford and Aberdeen Angus), than their cross breeds contemporaries. Lack of acces to water before the trip had affected more steers than cows. Improper method of herding, poor condition of the landing and longer journeys generated pH >= 5.8 in the meat. Plants features, animal's own characteristics, handling during loading and unloading, as well as elements associated with transport had effects that, in interaction, affected the pH of beef meat measured at 36 h postmortem.