A longitudinal study of the effect of time spent in lairage on salmonellas in the caecum and on the skin surface of 450 slaughter pigs from a single producer was conducted. Pigs were tested in 6 groups at 2 abattoirs, with one-third of a group being slaughtered after 18 h, one-third after 42 h and one-third after 66 h spent in lairage. The salmonella isolation rate from caeca and carcass surfaces increased significantly with increasing time spent in lairage. Salmonellas were isolated from the caeca of 18.5% of pigs held less than 24 h in lairage, 24.1% of pigs held a further 24 h and 47.7% of pigs held for 66 h in lairage before slaughter. The salmonella isolation rates from carcasses were 9.3%, 12.8% and 27.3% for the same groups. Thirteen salmonella serotypes were isolated from the caecal contents and carcasses over the 6 weeks of the trial. One abattoir had a higher salmonella isolation rate from pigs than the other and this was probably related to lairage management. It appeared that lairage is an important factor in the manipulation of the salmonella contamination of pig carcasses.

In a moist podzol type grey loam topsoil maintained under controlled conditions, persistence of inoculated Escherichia coli and Salmonella typhimurium cells was found to be similar with a death rate of about 14 days per log cycle. The death rate was not greatly affected by altering the growth conditions prior to inoculation of the soil. E. coli and S. typhimurium persistence was generally decreased in soil containing 85 % dry matter, with a rapid decline in cell numbers in soil containing more than 90% dry matter. E. coli survival was shown to be progressively reduced in soil: water mixtures containing less than 60% dry matter. Two of five different soil types tested were found to provide less favourable environments for inoculated cells, although soils of the same type collected on different occasions were not found to give consistent die-out rates. E. coli and S. typhzmurzum cells subjected to 14 days in dry soil were shown to have ability for regrowth when the soil was moistened.

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Erysipelothrix rhusiopathiae was isolated from 15 of 40 effluents collected from commercial piggeries. The organism was isolated from soil and pasture of experimental disposal sites for up to two weeks after application of effluent naturally infected with Ery. rhusiopathiae. The organism was more commonly isolated from soil than pasture. Times for 90% reduction (T90 values) of indicator organisms over a six week period following the effluent applications where Ery. rhusiopathiae was detected for 7 d or more, were 8–19 d for faecal coliforms in top soil and 5–12 d on pasture. T90 for faecal streptococci was 10–14 d in soil and 8–11 d on pasture. Laboratory investigations indicated that the death rate of Ery. rhusiopathiae was up to six times greater than Escherichia coli in soil at field capacity. In dry soil the differences in die‐out rate of the two organisms was less marked.