Influence of biosecurity on the occurrence of various enteric viruses in broiler flocks

Common enteric viruses affecting commercial broiler flocks include fowl adenovirus (FAdV), chicken parvovirus (ChPV), chicken astrovirus (CAstV), avian reovirus (ARV) and avian rotavirus (AvRV). To investigate their prevalence and to identify single and multiple infections we collected intestinal samples from 49 Austrian broiler flocks during necropsy of dead-on-farm birds twice during a production cycle (7–14 days and 28–35 days). Altogether, up to three consecutive clinically healthy flocks without signs of gastrointestinal disease were sampled from 17 different farms. Samples were analysed using virus isolation and PCR/RT–PCR methods. Virus prevalence was correlated with production data and on-farm biosecurity and management practices. Overall, ARV (75%) was most commonly detected in the flocks, followed by CAstV (61%), ChPV (61%), FAdV (57%) and AvRV (8%). Only in three (6%) flocks were none of the investigated enteric viruses detected. Flock infection profiles were very heterogeneous and included individual detection of the investigated viruses as well as different combinations thereof (up to all five investigated viruses). Even in the absence of clinical diarrhoea and/or macroscopic intestinal lesions, statistical analysis confirmed that the number of viruses detected had a significant economic impact characterised by poor weight gain and increased mortality, particularly due to the presence of FAdV, CAstV and/or ARV. Furthermore, the use of barn-specific clothing and/or footbaths as well as regular vermin control, resulted in lower prevalence of enteric viruses in the flocks studied. This highlights the importance of common biosecurity measures in poultry production to prevent economic losses. Detection timepoints and patterns indicate horizontal introduction of various enteric viruses.Flock infection profiles were very heterogeneous; no dominating virus profile.Broiler production was negatively affected by the number of enteric viruses detected.Common biosecurity measures had a significant negative effect on virus prevalence. Detection timepoints and patterns indicate horizontal introduction of various enteric viruses. Flock infection profiles were very heterogeneous; no dominating virus profile. Broiler production was negatively affected by the number of enteric viruses detected. Common biosecurity measures had a significant negative effect on virus prevalence.