Litter management strategies and their impact on the environmental and respiratory microbiome might influence health in poultry

Abstract

Aerial and respiratory tract-associated bacterial diversity has been scarcely studied in broiler production systems. This study examined the relationship between the environmental air and birds' respiratory microbiome, considering a longitudinal sampling. Total viable bacteria and coliforms in the air were quantified, and the 16S rRNA gene was sequenced from tracheal and air samples obtained through a novelty protocol. Air results showed a decrease in coliforms over time. However, at week 3, we reported an increase in coliforms (from 143 to 474 CFUc/m(3)) associated with litter management. Additionally, 16S rRNA gene results indicated a distinctive air microbial community, associated primarily with Bacillota phylum particularly of the Bacilli class (>58%), under all conditions. Tracheal results indicated a predominance of Escherichia coli/Shigella at the beginning of the productive cycle, shifting toward the middle and end of the cycle to Gallibacterium. However, at week 3, the dominance of Escherichia coli/Shigella (>99.5%) associated with litter aeration by tumbling stood out. Tracheal and air samples displayed a statistically different community structure, but shared differentially abundant features through time: Enterococcus, Gallibacterium, and Romboutsia ilealis. These results indicate the impact of production management protocols on the birds' respiratory system that should be considered a breakpoint in poultry farm health.