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

Abstract

SUMMARY: 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 to 9 wk 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 swabs 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.

Keywords

• laying hen
• free-range
• stocking density
• Salmonella
• Campylobacter
• Listeria