Serologically 56Æ3% of the pigs were found positive for Salmonella using a cut-off level of the optical density
percentage higher than 10 (O.D.% ‡ 10). While on individual pig level the correlation between the bacteriological
and serological data was poor, because of recent Salmonella infections, a better correlation was found at the herd
level on the moment of slaughtering