Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2009
Publication Date: N/A
Interpretive Summary: Housing systems for layer hens are under scrutiny by consumers who want eggs from birds raised in houses with good air quality. The purpose of this study was to compare caged (high-rise and manure belt) and non-caged layer houses for air quality, respiratory disease pathogens as well as the human food-borne pathogens, Campylobacter and Salmonella. Seasonal differences were observed. In the winter, environmental quality (ammonia levels and temperature) was best in the caged houses (high rise and manure-belt). In the summer, temperature fluctuations were minimal in the non-caged houses where birds had free access to the outdoors. Ammonia levels for all three housing systems during the summer months were similar. Using conventional bacteriological culture, in the winter months, the prevalence of Campylobacter spp. was highest in the non-caged houses when compared to caged birds. In the summer, however, Campylobacter spp. prevalence was highest in caged layer hens raised in the houses where manure was removed by conveyer belts. No differences between houses were evident for Salmonella. Likewise, no differences in the seroprevalence of Mycoplasma were noted among the houses during either winter or summer.
Technical Abstract: In this field observational study, three types of laying-hen houses, i.e., high-rise (HR), manure-belt (MB), and cage-free floor-raised (FR), were monitored for environmental temperature, relative humidity, carbon dioxide (CO2), and atmospheric ammonia (NH3) during winter and summer conditions in Iowa. Under winter conditions, temperature and NH3 levels were maintained at more comfortable levels in the HR and MB facilities than in the FR houses, where NH3 level reached 85-89 ppm and inside temperature more closely fluctuated with outside conditions. Under summer conditions, inside temperature showed the least rise above ambient in the FR facilities, and NH3 level was similar for all housing types. Examination of the hen health status revealed differences in pathogen frequency between housing systems for winter and summer, but not conclusively in favor of one system over another. The results of this observational study indicate that the benefits of each system were season-dependent. Further monitoring of the environment, bird health and production performance over an extended period (e.g., one year) to quantify the benefits and limitations of each system is warranted. Information of this nature will aid in optimization of hen housing systems for enhanced bird welfare and sustained production efficiency for the egg industry.