Purpose: The aims of this study were (i) to investigate the effects of slaughter process stages on the microbial carcass contamination, and (ii) to compare microbial loads on cattle carcasses and hides (carcass–hide ratios).
Methods: In two large-scale Swiss abattoirs, samples from 100 cattle carcasses examined at selected stages of slaughter (skinning, evisceration, trimming, washing, blast chilling) and from 100 hides and corresponding chilled carcasses were collected. Carcass and hide samples were obtained by swabbing from the neck, brisket, flank, and rump area and examined for total viable counts (TVC) and Enterobacteriaceae.
Results: On hides, average TVC was 5.6 log CFU cm-2 (abattoir A > abattoir B, difference 0.5 log CFU cm-2) and Enterobacteriaceae were commonly detected. After skinning, average TVC on carcasses was 1.5 log CFU cm-2 (abattoir A > abattoir B, difference 0.3 log CFU cm-2) and Enterobacteriaceae frequencies were <10%. After evisceration, trimming, and washing, minor changes (mainly increases) occurred. Blast chilling reduced microbial loads on carcasses from abattoir B, but reductions were limited in abattoir A (average TVC: 1.0 and 2.0 log CFU cm-2 in abattoir A and B, respectively). Carcass–hide ratios of the two abattoirs were comparable for TVC but differed for Enterobacteriaceae counts.
Significance: Average carcass contamination after skinning was low, levels slightly increased from skinned to washed carcasses, and the abattoir-specific effects of blast chilling were probably related to differences in the achieved surface desiccation. In the daily practice, carcass–hide ratios allow comparing slaughter process performance between abattoirs.