Despite routine utilization of standard vaccination protocols in broiler breeder and broiler flocks, outbreaks of diseases in broiler flocks still occur. However, limited data on pathogen prevalence and associated risk factors among commercial broiler flocks in Canada are available.
Dr. Michele Guerin, a Poultry Epidemiologist from the University of Guelph recently completed a comprehensive project that investigated the prevalence of nine viruses * and four bacteria of health significance for the Ontario broiler industry. The study included the associations of exposure to the pathogens with management and biosecurity practices, flock mortality, and condemnations.
“As a contribution to disease control initiatives, this study will enable producers to adopt better strategies to reduce the incidence of these pathogens within their flocks,” said Dr. Guerin in an interview.
Guerin’s team investigated 231 randomly selected Ontario broiler flocks and results showed frequent exposure to AAAV, ARV, CAV, pathogenic FAdV species, IBDV, Clostridium perfringens, and Enterococcus cecorum, and no exposure to, or low prevalence of, AEV, IBV, ILTV, NDV, Brachyspira spp., and Clostridium difficile.
Beyond prevalence, the genotypes of several of these pathogens were determined.
“Potentially pathogenic genotypes of FAdV, IBDV, and IBV were identified that can guide vaccine development and disease control efforts in Ontario,” she explains.
Although no specific management or biosecurity practice was identified as a predictor of all pathogens investigated, several factors were significantly associated with the prevalence of more than one pathogen (e.g. feed, barn and environmental conditions, hatchery, manure disposal, and antimicrobial use).
“Geographic and seasonal variation in the prevalence of a number of pathogens was evident,” Dr. Guerin indicated. “However no one district or season stood out as being a hot-spot or time period of high prevalence for all pathogens investigated.”
Of interest, a high proportion of Clostridium perfringens isolates were found to be resistant to antimicrobials commonly used in feed, and use of these antimicrobials was a risk factor in the development of resistance.
“Finding alternatives to the use of antimicrobials in the feed to prevent necrotic enteritis should continue to be a priority for the industry,” Dr. Guerin asserted.
Dr. Guerin highlights that of all the pathogens surveyed, only Clostridium difficile poses a potential risk of infection for humans via the food chain, and despite the fact that toxigenic strains were found among the isolates, the proportion of positive flocks was low.
This research was funded by the Animal Health Laboratory’s AHSI, Poultry Industry Council, OMAFRA- U of G Partnership, and Chicken Farmers of Ontario.
*Avian adeno-associated virus (AAAV), Avian encephalomyelitis virus (AEV), Avian reovirus (ARV), Chicken anemia virus (CAV), Fowl adenovirus (FAdV), Infectious bronchitis virus (IBV), Infectious bursal disease virus (IBDV), Infectious laryngotracheitis virus (ILTV), Newcastle disease virus (NDV).