Factors affecting the pH decline in lamb after slaughter.

Early postmortem pH has been linked to meat tenderness, especially in electrical stimulation and/or rapid chilling applications. In order to evaluate factors that affect pH, a trial was carried out in which 96 lambs were slaughtered over a period of 12 months. Carcass traits including age, sex and weight were recorded and the pH of M. longissimus thoracis et lumborum was measured at 0.5, 1.5, 4 and 24 h postmortem. Significant differences in pH were present over the 12 months but these differences could not be attributed to seasonal or age factors. The sex of the animal had no effect on early pH (0.5 h, 1.5 h) or final pH (24 h), but the 4 h pH of female lambs was lower than that of male lambs (P<0.001). Regression analysis, using 0.5 h pH and other measured traits, showed that individual male and female prediction models were better (R(2)=0.80 and RSD=0.10) for predicting 4 h pH than a combined model (R(2)=0.74 and RSD=0.11).