Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/10/2004
Publication Date: 4/20/2005
Citation: Hurd, H.S., Gailey, J.K., McKean, J.K., Griffith, R.W. 2005. Variable abattoir conditions affect Salmonella enterica prevalence and meat quality in swine and pork. Foodborne Pathogens and Disease. 2(1):77-81. Interpretive Summary: We compared Salmonella enterica prevalence among pigs held for short (15-45 min) versus long (up to 4 h) periods before slaughter; and correlated the type of flooring (slatted vs. concrete) with the S. enterica prevalence. S. enterica-positive samples were highest (p < 0.05) in the cecum of pigs held on solid concrete floors (72.4%) versus pigs held on slatted floors (63.3%); animals held for less than 45 min before slaughter had the lowest proportion of S. enterica-positive samples (52.9%). Meat quality, as measured by multiple parameters, was adversely affected by lack of a rest period. From this and other studies, it appears that elimination of the holding process as currently practiced by the U.S. pork industry is not a feasible S. enterica control option.
Technical Abstract: There is considerable evidence that abattoir holding pens pose a significant Salmonella enterica risk to swine immediately pre-harvest. The objective of this study was to compare S. enterica recovery rates from pigs slaughtered after a minimal holding time (15-45 min) to those held (~ 4 h) on slatted or solid concrete floors. It consisted of seven repetitions at a large volume (11,000 head/day) Midwest abattoir. Each repetition consisted of three treatments (30 pigs each): animals held for a short time (15-45 min) on a solid floor not normally used as a holding area (short-hold), animals held for 4 +/- 0.5 h on slatted, or solid concrete floors. Cecal contents (20 ml), feces (20 g), and the ileocecal lymph node (ICLN) were cultured for S. enterica. The effect of the three treatments on meat quality parameters (loin pH at 35 min and 6 h, color, drip loss) was evaluated for the first four replicates. The proportion of S. enterica-positive samples was highest (P < 0.05) in the cecum of pigs held on solid concrete floors (72.4%), followed by slatted floors (63.3%), then short-hold (52.9%). The pig prevalence, as measured by any one of the three samples being positive was significantly different (P < 0.05) between solid (81%) and short-hold (69%). Meat quality, as measured by multiple parameters, was adversely affected by lack of a rest period. The mean 24-h pH was significantly lower than the other two groups. The mean Minolta L (49.59) and the drip loss (3.619) were significantly higher in the short-hold group. This study demonstrates that pigs are exposed to S. enterica at multiple points in the pre-harvest environment, and immediate slaughter to avoid holding pen exposure is not feasible or cost-effective in current U.S. systems. Additionally, the 2- to 4-hour rest period appears critical for meat quality.