Methods for Evaluation of the Thermal Environment in the Animal-Occupied Zone for Weaned Piglets

Two evaluation methods are introduced for expression of the quality of the thermal conditions in theanimal-occupied zone (AOZ) in rooms for weaned piglets. One method uses only the AOZ temperature, while the other usesthe kata-value (KV), which combines air velocity and temperature and indicates the heat loss to the environment. AOZ thermalconditions should be within the thermo-neutral zone (TNZ) of the piglets. The methods use two new numerical indicators,based on the duration and the magnitude of excess of AOZ thermal conditions outside the TNZ: one referring to the numberof degree-hours (Ch), and the other to the number of kata-value-hours (KVh) during a batch. The objective was to evaluatethe two methods in a door-ventilated room for weaned piglets. In the experiment, temperature was measured in all ten pensof a room and air velocity in three pens during eight successive batches, together lasting about one year. Pens closer to theair inlet had higher temperatures and lower KV than pens in the back of the room. Momentary temperature difference betweenpens reached up to 7C. During the first days of most batches, pen conditions in the back of the room were too cold. Atthe end of most batches, pen conditions in the middle of the room were too warm. The value of the two indicators variedper pen and per batch from 0 to 319Ch (0 to 219 KVh) too cold and from 0 to 602Ch (0 to 793 KVh) too warm. Fortoo warm conditions, there was a significant (P < 0.001) and strong correlation between the two indicators (R2 > 0.96),but not for too cold conditions (R2 > 0.48). Therefore, measuring air velocity in addition to temperature in the AOZ forrecognition of too cold conditions had surplus value. Excluding outliers from one extremely warm batch, the maximumvalue of the indicator for too warm was 65Ch. This indicator significantly affected the feed conversion ratio, whichincreased with 0.0024 kg/kg per Ch, and daily growth and daily feed intake, which decreased with 0.0022 kg/animal and0.0030 kg/animal, respectively, per Ch. The methods presented are useful tools in the technical evaluation of climate systemsand for a more optimal climate control in the AOZ.