Microbiological Air Contamination in Different Types of Housing Systems for Laying Hens

Silvana POPESCU, Cristin BORDA, Eva DIUGAN


The aim of this paper was to assess the microbiological contamination levels of indoor air in two housing systems for laying hens, enriched cages and noncage (deep litter) systems. The correlation of airborne bacteria and fungi with the environmental parameters (temperature, relative humidity, air flow velocity) was investigated. The number of bacteria (mesophile, staphylococci, streptococci and gram-negatives) and fungi was determined in 10 farms through specific methods. The results were statistically processed by using the SPSS software, version 17. The number of bacteria and fungi varied in the 10 laying hen houses, ranging from 7.70×104 CFU/m3 to 4.80×106 CFU/m3 for the total number of mesophilic bacteria, from 1.99×104 CFU/m3 to 3.11×106 CFU/m3 for staphylococci, from 1.26×104 CFU/m3 to 8.94×105 CFU/m3 for streptococci, from 1.09×103 CFU/m3 to 9.65×104 CFU/m3 for gram-negatives and from 3.31×103 CFU/m3 to 9.06×104 CFU/m3 for fungi. The numbers of bacteria and fungi were significantly higher (P < 0.001) in farms with noncage systems. The proportions of groups with hygienic significance within the total mesophilic bacteria numbers were within the admitted limits in all of the farms, with the exception of staphylococci, which slightly exceeded the recommended values in the noncage system. Significant correlations (P < 0.001) were found between the concentrations of the bacteria and fungi and the temperature and relative humidity of the air. The results of this comparative study show a high level of airborne microbial contamination in laying hen farms with noncage systems. 

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