G. Gustafsson

Release of heat, moisture and carbon dioxide in an aviary system for laying hens

Abstract 1. Production of total heat, divided into sensible and latent heat, together with carbon dioxide and animal activity were determined at different ambient temperatures under full-scale conditions in an aviary system with loose-housed laying hens. 2. Sensible heat production decreased approximately linearly with increasing ambient temperature and was lower during the day than at night. One explanation may be that some sensible heat produced by the hens was converted to latent heat by evaporation of moisture due to increased activity of the hens during the day (scratching in the bedding and drinking/waste water). 3. Latent heat production increased with increasing ambient temperature and was higher during the day than at night. This confirms that the hens, by agitating the bedding during the day and by spilling drinking water, transferred some sensible heat to latent heat by evaporation. 4. Total heat production decreased with increasing temperature because the hens by thermoregulation decreased their metabolism in order to maintain a constant body temperature. The difference between day and night values of total heat production was less pronounced than in the case of sensible and latent heat. In comparison with current guidelines the measurements showed a higher total heat production (22% higher at 20°C). 5. There was a large diurnal variation in carbon dioxide production, closely correlated to measured animal activity; on average carbon dioxide production during the 12-h dark period was only 66% of the production during the day.

Use of solar collectors for drying agricultural crops and for heating farm buildings

Abstract The main applications for solar collectors in agriculture are drying of agricultural crops and for the heating of animal houses with great energy demands. Different types of active airtype solar collectors have been examined for these applications. In both cases there are benefits if the solar collector is integrated into the building. The types which have been tested have the potential to compete economically with oil as a heat source.

Gaseous Emissions from a Fattening Piggery and a Dairy Barn with an Automatic Milking System

The concentrations of CH4, N2O, CO2 and NH3 were measured with a photoacoustic multi-gas analyser 1412 and a multiplexer 1309 (Lumasense Technologies A/S, Ballerup, Denmark) in a piggery over two fattening periods (spring and autumn) and in a dairy cow barn (spring). The aim was to quantify the emissions and to study factors affecting the emissions. The mechanically ventilated piggery was a slurry-based small scale research facility with a partly slatted floor and daily manure removal with scrapers. It housed 50 and 54 fattening pigs per batch in spring and in autumn, respectively, with a weight gain of 0.86–0.94 kg pig-1 day-1. The dairy cow barn was naturally ventilated and had cubicles and a solid sloping floor with a central urine gutter. The floor was scraped once every hour during the daytime and once every two hours at night. It housed 108 Holstein dairy cows, which were milked by an automatic milking system (AMS). The average milk production was 31.5 kg milk cow-1 day-1.

Methods to reduce airborne dust in a loose-housing system for laying hens.

How different factors and techniques affect concentration and generation of dust in a floor housing system for laying hens were investigated in a climate chamber. The efficiencies of different dust reducing measures were investigated.

Odor and Ammonia Release at Different Climatic Conditions in a Loose Housing System for Layers

Loose housing systems are being re-established in Sweden since animal welfare legislation stipulates that systems for laying hens must include laying nests and perches and provide access to litter. Compared to traditional cage systems the air in loose housing systems may be more polluted since gases are emitted from large exposed surfaces of manure and litter. Different ventilation and control strategies for animal houses may beside differences in indoor climate and pollution concentrations also result in differences in odor and ammonia emissions. In order to study variation of emissions and concentrations a small scale poultry house (climate chamber) at the university research station Alnarps Sodergard was equipped with a loose housing system were about 400 layers were kept. Temperature was set to about 12, 15, 20, and 25 °C and ventilation rate was set to values between 0.9 and 5.3 m3/(h hen). Temperature, humidity, and ventilation rate were measured together with concentrations of sampled odor, ammonia, carbon dioxide and dust. Odor emission showed a significant increase with temperature at similar ventilation rate. Odor and ammonia emissions were more strongly correlated to water vapor pressure than to relative air humidity. Both odor and ammonia emission showed a significant increase with water vapor pressure. The ammonia concentration was high and exceeded 25 ppm in many of the measurements.