Air Quality in Cage-free Houses during Pullets Production

Abstract

<b><sc>Abstract.</sc></b> The primary food chains and grocers have pledged to only source cage-free (CF) eggs by 2025 or earlier due to concerns on animal welfare of laying hens in conventional cages. As compared to conventional cage systems, an inherent challenge with CF housing is the poor indoor air quality, i.e., high ammonia (NH3), particulate matter (PM) and airborne bacteria (AB) levels. Studies have been conducted on commercial cage-free farms during lay period, but limited studies investigated the air quality during pullet phase. The primary objective of this study was to examine the effect of birds‘ age and behaviors on PM levels in the CF housing system. About 800 Hy-line W-36 commercial day-old chicks were randomly allocated into four identical rooms (7.3 m L * 6.1 m W), which were assigned with similar feed, water, lighting, and bedding. The dust data were measured twice a week at three different locations, i.e., near perch, between feeder and drinker, and near exhaust fan of each room, with TSI dust monitor (Model 8533). Ammonia concentrations were monitored with DOL-53 sensors and Onset HOBO RX3000. The dust of PM_2.5, PM₁₀, and total suspended particles (TSP) increased significantly as birds age from one to eleven weeks. For instance, PM_2.5was 0.023 mg/m³ on the first week. The levels increased to 0.596 mg/m³ by 11 weeks of old. In addition, dust levels measured near perches were three time higher than that measured between feeder and drinker or near the exhaust fan (p<0.001). The significant interaction between the age of pullets and dust levels was developed (p<0.001). For NH3 levels, the average daily concentration was <1 ppm as of 11 weeks of age for all rooms due to dry litter conditions (e.g., 9-10% litter moisture content).