Advice on Salmonella control at hatcheries initially worked to reduce contamination but the success was not maintained over the long-term, according to a study.
Researchers investigated the Salmonella status of 23 broiler hatcheries in Great Britain and the changes in prevalence and distribution of Salmonella in contaminated sites after guidance on control was provided.
Results indicate that broiler chicken hatcheries still pose a risk for Salmonella dissemination in the industry, said the study published in the journal Zoonoses and Public Health.
Visits took place between August 2016 and September 2019, with each hatchery sampled at least once. Ten sites were selected for repeat sampling to assess the impact of advice on the control of Salmonella, and these were visited between an additional one to five times.
After each visit, advice was given to the hatchery manager in a written report. It focused on biosecurity and hygiene measures observed, and how this related to Salmonella control. The advice was provided on disinfectant usage, cleaning and disinfection procedures, the hatchery’s workflow, and waste management.
The extent to which it was followed was based on conversations with hatchery managers and observations by sampling staff at follow-up visits. When followed in full, the advice was associated with a reduction in contamination.
Low but persistent contamination
The number of samples collected ranged from 108 to 421 per visit. In the 41 sampling trips to 23 hatcheries, 14 different Salmonella serovars were found.
There was low-level Salmonella contamination in some hatcheries. The prevalence of positive samples ranged from 0 to 33.5 percent between sites. At the first visit, Salmonella was isolated from 8.5 percent of samples.
At least one Salmonella serovar was isolated from 18 of the hatcheries visited, while more than one was recovered from 10 of them. From one site, seven different serovars were isolated during two visits.
The study found it was difficult to eradicate Salmonella from contaminated hatcheries, but reductions in prevalence are possible with improvements to biosecurity, cleaning and disinfection.
Salmonella 13,23:i:- was the top isolated type followed by Salmonella Senftenberg, Mbandaka and Montevideo.
Factors that influence the risk of contamination include the size or production volume, the standard of hygiene management, Salmonella status of the supplying breeder flocks, and the purchase of imported eggs to satisfy peaks in demand.
Samples taken from setter incubator areas were more likely to be positive for Salmonella than egg handling and egg transfer areas but less likely than other locations like chick handling and hatcher areas, the macerator area, tray wash/stores areas, external sites, and other waste handling areas.
Contamination was often found after cleaning and disinfection in hatcheries with significant problems.
Repeat visit findings
The interval between follow-up visits ranged from two months to two years with an average of 8.5 months. Time between the first and second visits ranged from 2 to 24 months, and between 2 and 11 months for the second and third visits.
In eight of the 10 hatcheries that had follow-up sampling visits plus advice on cleaning and disinfection, there was a significant reduction in Salmonella prevalence between the first and second visits. However, at the third visit, an increase was seen compared with the earlier visits.
It is possible that in some hatcheries, recommendations were no longer followed rigorously by the third sampling visit after initial reductions in Salmonella had been achieved, and in some sites the management team had changed, said the study.
The most common fault was a failure to use disinfectants at a concentration effective for Salmonella. Increases in hatchery throughput in some cases resulted in reduced cleaning standards and insufficient drying time between washing and disinfection, which diluted applied disinfectants.
Decisions on disinfection practices were largely driven by time pressure, cost, corrosion of equipment or health and safety concerns. The most common fault with tray washers was not operating them at a temperature that avoids the establishment of Salmonella because of concerns about energy costs and the generation of steam.
Recommendations to control Salmonella in commercial broiler hatcheries include taking care when sourcing eggs from outside the company and applying proven cleaning and disinfection protocols using effective disinfectants at adequate concentrations. Particular attention is needed to prevent recontamination of hatchery equipment and biosecurity practices should cover external areas.
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