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Dust sprinkling as an effective method for infecting layer chickens with wild-type Salmonella Typhimurium and changes
Samiullah Khan1, Andrea R McWhorter1, Daniel M Andrews2
1School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia.
Abstract:
Role of dust in Salmonella transmission on chicken farms is not well characterised. Salmonella Typhimurium (ST) infection of commercial layer chickens was investigated using a novel sprinkling method of chicken dust spiked with ST and the uptake compared to a conventional oral infection. While both inoculation methods resulted in colonisation of the intestines, the Salmonella load in liver samples was significantly higher at 7 dpi after exposing chicks to sprinkled dust compared to the oral infection group. Infection of chickens using the sprinkling method at a range of doses showed a threshold for colonisation of the gut and organs as low as 1000 CFU/g of dust. Caecal content microbiota analysis post-challenge showed that the profiles of chickens infected by the sprinkling and oral routes were not significantly different; however, both challenges induced differences when compared to the uninfected negative controls. Overall, the study showed that dust sprinkling was an effective way to experimentally colonise chickens with Salmonella and alter the gut microbiota than oral gavage at levels as low as 1000 CFU/g dust. This infection model mimics the field scenario of Salmonella infection in poultry sheds. The model can be used for future challenge studies for effective Salmonella control.
Insights
Chicken farm dust effectively transmits Salmonella Typhimurium (ST). Dust sprinkling led to higher Salmonella loads in organs than oral infection, establishing a new model for poultry research.
Area of Science:
- Veterinary Microbiology
- Poultry Science
- Food Safety
Background:
- Salmonella transmission via dust in poultry houses is poorly understood.
- Effective experimental models are needed to study Salmonella infection in chickens.
Purpose of the Study:
- To investigate the role of chicken dust in Salmonella Typhimurium (ST) transmission.
- To compare ST uptake via dust sprinkling versus conventional oral infection.
- To establish a novel, field-relevant infection model for poultry.
Main Methods:
- Commercial layer chickens were inoculated with ST-spiked dust via sprinkling or oral gavage.
- Salmonella loads in intestines and livers were quantified at 7 days post-infection (dpi).
- Gut microbiota composition was analyzed using caecal content analysis.
Main Results:
- Both methods led to intestinal colonization; dust sprinkling resulted in significantly higher liver Salmonella loads at 7 dpi.
- A colonization threshold as low as 1000 CFU/g dust was observed for gut and organ infection.
- Dust sprinkling and oral gavage similarly altered caecal microbiota compared to controls.
Conclusions:
- Dust sprinkling is an effective method for experimental Salmonella colonization in chickens, mimicking field conditions.
- This novel model effectively transmits Salmonella and alters gut microbiota, even at low dust concentrations.
- The model provides a valuable tool for future Salmonella control studies in poultry sheds.
