Risk assessment of intervention strategies for fallen carcasses in beef slaughter establishments

In the slaughter establishment, cattle carcasses move along the line attached to a slaughter chain. Cattle carcasses fall off the slaughter chain infrequently, but such an event results in carcasses potentially contaminated with bacteria that exist on floors and equipment. Microbes in the feces and ingesta of slaughtered livestock as well as microbes on the hide surfaces of those livestock contaminate the slaughter environment. This environment often will include important foodborne pathogens, such as Escherichia coli O157:H7. This analysis uses a risk assessment modeling approach to assess the potential public health effects of standardizing treatments for carcasses that fall off the slaughter chain at dehiding. This assessment examines combinations of six intervention options: 1) water rinse, 2) organic acid rinse, 3) trim, 4) organic acid rinse and trim, 5) carcass trimming and cook, 6) condemn the carcass. Potential improvement in public health results from progressive removal of the least effective of these intervention options. The results of this analysis indicate that the number of annual human E. coli O157:H7 illnesses avoided varies based on intervention type—organic acid rinsing (281), carcass trimming (787), organic acid rinsing plus trimming (1533), trimming plus cooking (1539), and carcass condemnation (1520). The model suggests that the numbers of illnesses prevented are largest and similar when either the organic acid plus trim, trim plus cook, or condemn interventions are set as the minimum. This conclusion was robust to sensitivity analysis of various uncertainties in the model. Interestingly, it was found that a universal condemnation of fallen cattle was not a necessary intervention. Although it was assumed that most large slaughter establishments currently implement a trimming plus cooking intervention for all fallen carcasses, the model suggests there is little difference among the three best interventions.