Impact of paddock area stocking density of free-range laying hens on egg and environmental microbiology.

Authors: Garcia, Javier; ANDERSON, KENNETH - North Carolina State University; Guard, Jean; Gast, Richard; Jones, Deana

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2023
Publication Date: 3/1/2023
Citation: Garcia, J.S., Anderson, K.E., Guard, J.Y., Gast, R.K., Jones, D.R. 2023. Impact of paddock area stocking density of free-range laying hens on egg and environmental microbiology. Journal of Applied Poultry Research. https://doi.org/10.1016/j.japr.2023.100338.
DOI: https://doi.org/10.1016/j.japr.2023.100338

Interpretive Summary: Free-range poultry has become more popular due to consumer demands for improvements in animal welfare. The aim of this study was to determine if paddock area stocking density had an impact on the egg and environmental microbiology of free-range laying flocks. A flock of brown egg layer was split and raised on either low- or high- paddock area stocking densities. Every 7-9 weeks between 20 and 52 weeks of age, egg and environmental samples were taken to determine the levels of aerobic bacteria, Enterobacteriaceae, and yeast and mold. Detection of pathogens such as Campylobacter, Listeria and Salmonella was also performed. At 20 weeks, the egg shells from high-density flocks had higher levels of aerobic bacteria and Enterobacteriaceae compared to the low-density flocks. However, by 44 weeks, the nestbox swaps from low-density flocks had higher levels of aerobic bacteria and Enterobacteriaceae. In the nestbox swabs, high-density flocks had a higher prevalence of Campylobacter compared to the low-density flocks. There were no differences in the prevalence of Listeria or Salmonella in this study. Previous study have shown differences in range usage and behavioral expression between flocks raised in low-and high- density flocks. The difference observed in this study could be impacted these changes. Further research is need to determine the relationship between hen behavior and egg and environmental microbiology of free-range laying flocks. Free-range poultry has become more popular due to consumer demands for improvements in animal welfare. The aim of this study was to determine if paddock area stocking density had an impact on the egg and environmental microbiology of free-range laying flocks. A flock of brown egg layer was split and raised on either low- or high- paddock area stocking densities. Every 7-9 weeks between 20 and 52 weeks of age, egg and environmental samples were taken to determine the levels of aerobic bacteria, Enterobacteriaceae, and yeast and mold. Detection of pathogens such as Campylobacter, Listeria and Salmonella was also performed. At 20 weeks, the egg shells from high-density flocks had higher levels of aerobic bacteria and Enterobacteriaceae compared to the low-density flocks. However, by 44 weeks, the nestbox swaps from low-density flocks had higher levels of aerobic bacteria and Enterobacteriaceae. In the nestbox swabs, high-density flocks had a higher prevalence of Campylobacter compared to the low-density flocks. There were no differences in the prevalence of Listeria or Salmonella in this study. Previous study have shown differences in range usage and behavioral expression between flocks raised in low-and high- density flocks. The difference observed in this study could be impacted these changes. Further research is need to determine the relationship between hen behavior and egg and environmental microbiology of free-range laying flocks.

Technical Abstract: Free-range poultry has become more popular due to consumer demands for improvements in animal welfare. The current study was conducted to determine the impact of paddock area stocking density on the egg and environmental microbiology of free-range laying flocks. A flock of brown egg layers was split and maintained at low- (4.02 m2/bird) and high- (2.01 m2/bird) paddock area stocking densities. Egg and environmental samples were taken every 7-9 weeks between 20 and 52 weeks (wk) of age for the enumeration of aerobic bacteria, Enterobacteriaceae, yeast and mold as well as the presence of Campylobacter spp., Listeria spp. and Salmonella spp. At 20 wk, shells from high-density flocks had higher levels of aerobic bacteria (P < 0.02) and Enterobacteriaceae (P < 0.008) compared to low-density flocks. However, at wk 44, nestbox swaps from low-density flocks had higher levels of aerobic bacteria and Enterobacteriaceae. Nestbox swabs (P < 0.04) of high-density flocks (43.3 %) had a higher prevalence of Campylobacter compared to low-density flocks (26.7 %). Differences in prevalence of Listeria or Salmonella were not observed in this study. Previous studies had shown differences in range use and behavioral expression between low- and high- paddock area stocking density free-range hens. These differences could have impacts on egg and environmental microbiology. Further research is needed to investigate the relationship between hen behavior and egg and environmental microbiology of free-range laying flocks.