The effect of different on-line dressing practices on microbiological and visible contamination of lamb carcasses

Three dressing practices were assessed in traditional lamb carcass dressing systems for their ability to improve control of microbiological and visible contamination. The routine removal of a piece of skin from the perineal area reduced total aerobic plate counts and Escherichia coli counts on carcasses derived from both woolly and shorn groups of lambs. Similar results were found when the "Y-cut" was delayed in the dressing sequence, but E. coli counts increased slightly in one group. The use of a wide-blow shear prior to the opening cut on the hindleg of carcasses derived from woolly lambs resulted in a slight increase in the microbiological contamination on the leg. The removal of a piece of skin from the perineal area reduced scores for faecal contamination despite a small increase in contamination with wool. Changes in visible contamination in response to the two other dressing procedures were principally effected through changes in levels of contamination with wool. Irrespective of dressing procedures, levels of microbiological and visible contamination were lower on carcasses derived from shorn compared with woolly lambs. These studies demonstrated that, although they are reasonable indicators, the use of parameters of visible contamination as a measure of carcass hygiene must be treated with caution. This is especially the case if a genuine HACCP-based system for the control of dressing hygiene for a particular class of slaughtered livestock is to be implemented.