Improving layer housing by following the microbes.

April 24, 2023

1 Min Read
Poultry scientists examine microbes in free-range layer environment
monticelllo / iStock

A new study in the Poultry Science Association’s The Journal of Applied Poultry Research provides important data on how free-range stocking density affects the risk of spreading microbes via birds or their eggs. The research shows that potentially harmful microbes can spread even in low stocking density conditions.

The research team, from the U.S. Department of Agriculture and North Carolina State University, worked with 300 Hy-line Brown laying hens housed in at a low stocking density (4.02 m2/bird) or a high stocking density (2.01 m2/bird). The team collected environmental and egg samples every seven to nine weeks when the hens were between 20 and 52 weeks old.

Key findings:

  • High stocking density housing had higher presence of aerobic bacteria (such as Enterobacteriaceae) at week 20; however, the aerobic bacteria levels in the low stocking density ranges caught up soon after that.

  • Surprisingly, the low stocking density housing had a higher presence of Enterobacteriaceae by the end of the study period, but the eggs collected from the high stocking density housing had more Enterobacteriaceae.

  • The researchers noted no significant differences in yeast or mold contamination between the two stocking densities, nor did they find differences in Salmonella or Listeria levels.

So, is one stocking density better than another? Finally answering that question may come down to taking a closer look at hen behavior.

The Poultry Science Association (PSA) is a professional organization consisting of approximately 2,000 educators, scientists, extension specialists, industry researchers, administrators, producers, and college students who are committed to advancing the poultry industry.

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