[Prevalence of Salmonella enteritidis and Salmonella typhimurium in laying hen flocks battery and on floor housing. Comparative studies using bacteriological and serological demonstration methods].
The prevalence of Salmonella (S.) enteritidis and Salmonella typhimurium is described in 34 flocks of laying chickens. In an attempt to detect the rate of infection comparative bacteriological and serological methods were employed. By cultural methods 47.0% of the floor flocks and 35.3% of the battery flocks were S.e. or S. tm. infected. The same tendency was established with the Bommeli ELISA. Flocks on floor were positive in 64.7% and flocks in batteries were positive in 47.0%. Both methods--bacteriological isolation and serology--yielded more S.e. positive flocks kept on the floor than in battery systems. Long-term studies of four flocks demonstrate a long persistence of antibodies against S.e. in serum and yolk even after one year. Almost all S.e. infected flocks prove a correlation between increase of positive cultures and antibody positive sera. Also, a correlation between levels of absorption values of sera tested in the Bommeli ELISA and positive fecal samples is evident. This is particularly true for eight of 10 flocks. If S.e. infected laying flocks need to be detected, then high absorption values in sera or yolk and a high rate of antibody positive hens provide reasonable good conditions to attempt subsequent bacteriological examinations.