The effect of defined stress levels on primary microbial contamination of slaughtered pigs

The effects of premortal stress situations on the endogenous microbial primary contamination of organs and muscles were recorded in 101 normally slaughtered pigs. The quantitative microbiological examination revealed bacteria in 98 % of liver samples, and an aerobic total microbial count of 104 CFU/g in 25 % of samples. 75 % of muscle samples were negative, with the remaining samples having a total microbial count of up to 102 CFU/g. No pathogenic bacteria were detected. The quantitative microbiological results showed no correlation with the stress levels recorded on the basis of the infection-induced pathologic-anatomic lung findings. Nor could any correlations be established with the mean values determined for heart frequency or with the stab test values for cortisol, adrenalin and noradrenalin. Lower total microbial counts were recorded in the livers of animals slaughtered immediately after transport with no rest period than in those of animals with a rest period. Further studies are needed to determine whether more pronounced physical and mental stress has any impact on endogenous contamination of the organs.