Re-used or New Bedding Are Not Drivers of Salmonella Levels and Serovar Emergence in Commercially Farmed Broilers in Australia

Abstract

To inform Salmonella on-farm management during broiler rearing, a 2-year study on two farms compared the Australian practices of new bedding use, partial litter re-use and an alternative, full litter re-use. Six sequential commercial cycles of ~50 days each were tested on each farm, on ~day 7 from placement (litter only), prior to first thin-out, and prior to final removal (litter and ceca). A random number sample collection occurred, defined by shed supports (33, 39), different drinkers, feeders, and shed center. Across the six cycles on both farms, Salmonella levels in ceca just prior to thin-out on full re-use litter were higher (log 3.11 MPN/g, P = 0.008) than for new bedding (log 2.04 MPN/g) and partial re-use (log 2.43 MPN/g) litter (the latter two were not significantly different). Prior to final removal across all practices the Salmonella levels in ceca from new bedding (log 1.72 MPN/g), partial re-use litter (log 1.77 MPN/g), and full re-use litter (log 2.33 MPN/g) were not statistically different, suggesting no effect of litter practice. The Salmonella levels in litter prior to the first (log 1.96–2.31 MPN/g) and second (log 2.24–2.48 MPN/g) removals were also not statistically different. The emergence of Salmonella serovars in the partitioned chicken-free grow-out end (back) of all sheds at ~day 7 did not suggest carry-over. Both the pattern of emergence of Salmonella serovars and Salmonella levels in litter ~day 7 in the brooder-end with chickens (front), suggested the Salmonella present were due to flock contribution and not practice driven. The dominant Salmonella serovar across cycles on both farms was S. Sofia (75 and 77% isolates) followed by S. Typhimurium (11 and 17%). Irrespective of initial serovars, Salmonella Sofia rapidly gained dominance and displaced 14 other serovars including S. Typhimurium on both farms. This study demonstrates that the litter practices are not the major driver of Salmonella prevalence in broiler farming, supporting the commercial re-use of bedding as a sustainable farming practice in Australia. The major contributor of Salmonella load in production is the Salmonella status of the incoming flock, indicating this is the key area to focus future control measures.

Broiler farming practices using new or re-used bedding, inclusive of free-range, have no impact on <i>Campylobacter</i> levels, species diversity, <i>Campylobacter</i> community profiles and <i>Campylobacter</i> bacteriophages

“…In a climate of dwindling bedding resources, litter re-use, supported by pathogen reduction between cycles, contributes to sustainable farming [2] . Whilst litter re-use is adopted across four Australian states [3] , in Queensland it has been a long-term practice for over 30 years [4] . Litter is also re-used in other countries such as the USA [5] , [6] .…”

“…Litter is also re-used in other countries such as the USA [5] , [6] . Previous studies have investigated the Australian practice of partial litter re-use, including a detailed analysis of in-shed management with a focus on both Campylobacter and Salmonella [4] , [7] – [9] . In Australia, free-range chicken meat and egg production is becoming more popular due to the demand for pasture/range raised birds [10] , and in other countries because of emerging consumer preferences [11] .…”

Management and environmental factors influence the prevalence and abundance of food-borne pathogens and commensal bacteria in peanut hull-based broiler litter

“…Understanding broiler management factors that could be used to predict the occurrence of food-borne pathogens in reused litter is vital to limiting their prevalence in post-harvest chicken production. Although there are studies on the microbiology of reused litter, these studies have been limited to wood shavings and rice-hull based litter ( Kelley et al, 1995 ; Brooks et al, 2010 ; Roll et al, 2011 ; Volkova et al, 2011 ; Chinivasagam et al, 2012 ; Eberle et al, 2013 ; Roberts et al, 2013 ; Wei et al, 2013 ; Brooks et al, 2016 ; Rauber Wurfel et al, 2019 ; Voss-Rech et al, 2019 ; Valeris-Chacin et al, 2021 ; Chinivasagam et al, 2022 ).…”