The dynamics of Salmonella occurrence in commercial laying hen flocks throughout a laying period

Jochen Schulz (1) , Sebastiaan van Hoorebeke (2) , Birthe Hald (3) , Jörg Hartung (4) , Filip van Immerseel (5) , Ines Radtke (4) , Susanne Kabell (6) , Jeroen Dewulf (2)

1 Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour
2 Obstetrics, Reproduction and Herd Health
3 Department of poultry, fish and fur animals
4 University of Veterinary Medicine Hannover, Foundation, Germany, Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour
5 Pathology, Bacteriology and Avian Diseases
6 Dept. for Fish- and Animal Health

Contaminated eggs and egg products have been recognised since many years as an important source of Salmonella infections in humans in the European Union and in the United States. Longitudinal studies can help to increase our knowledge about the dynamics of the occurrence of Salmonella in the course of a laying period. The total of 41 laying hen flocks, 18 in Belgium, 6 in Denmark and 17 in Germany were followed during an entire laying period. Samples taken from the empty cleaned and disinfected poultry houses were all negative for Salmonella. After hens arrived on the farms five pooled faecal samples, one pooled dust sample and 40 cloacal swabs (Belgium and Germany) or 40 swabs from fresh droppings (Denmark) were taken four times from 18 flocks, three times from 21 flocks and two times from 2 flocks in the course of the laying period. Ten flocks (two Belgian and eight German flocks) were tested up to three times positive for Salmonella. Forty three out of 50 positive samples contained Salmonella Enteritidis phage type 4 (29 isolates) or phage type 8 (14 isolates). The probability of subsequent Salmonella positive findings increased significantly in Salmonella positive flocks (p < 0.05, odds ratio = 6.4). However, the probability of finding Salmonella did not depend on the time of sampling in the laying period or the season.

Mots clés: Life Sciences

Domaines: Biologie animale

Jochen Schulz, Sebastiaan van Hoorebeke, Birthe Hald, Jörg Hartung, Filip van Immerseel, et al.. The dynamics of Salmonella occurrence in commercial laying hen flocks throughout a laying period. Avian Pathology, 2011, 40 (03), pp.243-248. ⟨10.1080/03079457.2010.544290⟩. ⟨hal-00710047⟩