This project was unable to demonstrate a protective effect of All in-All out (AIAO) over continuous flow production systems for swine from organisms of food safety interest at the abattoir. It provided valuable information about the ecology of Salmonella spp., Campylobacter spp. and Yersinia enterocolitica on farms and the abattoir. Implanted electronic microchips have been demonstrated as feasible for carcass identification from farm to abattoir cooler. Doubts about predictive values of commonly used detection procedures for on-farm prevalence of these organisms are raised. A new paradigm to explain the nexus of on-farm activities on the microbiologic status of pigs presented to the abattoir is advanced. These studies may substantially refocus farm to abattoir HACCP plans for microbial contamination. I