Does built-up litter competitively exclude Salmonella: What have we learned from Salmonella Heidelberg?

Authors: Oladeinde, Adelumola - Ade; Cook, Kimberly - Kim; ABDO, ZAID - Colorado State University; AGGREY, SAMMY - University Of Georgia; Looft, Torey; REHMAN, MUHAMMAD - Agriculture And Agri-Food Canada; DIARRA, MOUSSA - Agriculture And Agri-Food Canada; RITZ, CASEY - University Of Georgia; Cox Jr, Nelson; Hinton Jr, Arthur

Submitted to: International Poultry Scientific Forum
Publication Type: Abstract Only
Publication Acceptance Date: 12/2/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The practice of reusing “built-up” litter to raise multiple flock of chickens is known to promote the competitive exclusion of food-borne pathogens including Salmonella, however the mechanism and the microbiome associated with this process is poorly understood. Moreover, the general shift towards antibiotic-free live broiler production indicates the need for efficient litter management practices and the development of new antimicrobials alternatives for use in pre-harvest poultry. Using Salmonella enterica serovar Heidelberg (S. Heidelberg) as a pathogen-model and Big Data (Genomics, transcriptomics and metagenomics) generated from a series of in vivo and in vitro inoculation studies with “built-up” litter (bedding material that is intended for reuse on subsequent flock), we gained a better understanding of the interactions between the gut microbiome, litter microbiome and antibiotic resistance transfer in broiler chickens raised without antibiotics. Our results show that “built-up” litter reused after an adequate downtime (greater than 2 weeks between consecutive flocks, during which the broiler house is empty) harbors a stable and predictable microbiome dominated by the families Nocardiopsaceae and Bacillaceae. Members of these families were associated with a reduction in S. Heidelberg survival in reused litter (up to 6-log reduction). However, when day of hatch Cobb broilers were raised on “built-up” litter versus fresh pine shavings, Bifidobacteriaceae was the family associated with a lower rate of gut colonization (fresh = log 2.85±1.1 g/ceca ; reused=log 2.46 ± 0.8 g/ceca) and acquisition of resistance to tetracyclines and aminoglycosides (n = ~ 300 isolates; fresh = ~ 38.45 %; reused = <1%) by S. Heidelberg. Further, litter physicochemical parameters such as ammonia, pH, moisture and water activity were significantly correlated with the microbiome present in litter. Together, our study supports the notion that the practice of litter reuse promotes an “unfavorable” environment for Salmonella, therefore limiting their potential for survival or acquiring antibiotic resistance.