Linear Models for the Prediction of Animal Zone Ammonia in a Weaned Piglet Building.

Measuring ammonia inside livestock buildings poses many challenges that hinder the incorporation of this variable into environmental control systems. The aim of this study was to measure various microclimate variables inside a weaned piglet building and analyse their interactions with NH₃ concentrations for setpoint temperatures of 26 and 25 °C, in order to control NH₃ concentrations based on other easily measurable variables. The experimental test was conducted on a conventional farm in Northwest Spain. NH₃ concentrations in the animal zone were best correlated with CO₂ concentrations in the animal zone (R = 0.91 and R = 0.55) and velocity of air extracted through the fan (R = 0.72 and R = 0.65) for setpoint temperatures of 26 and 25 °C, respectively. Similarly, strong correlations were found with relative humidity in the animal zone and temperature of inlet air. Because NH₃ concentration in the animal zone is related to the performance of the ventilation system, strong positive correlations were found between NH₃ concentration and temperature of inlet air whereas negative correlations were found between NH₃ concentration and ventilation rates. Linear regression models based on CO₂ concentrations in the animal zone and temperature of inlet air are recommended, because they provide a good fit for both setpoint temperatures using variables that can be readily measured. [ABSTRACT FROM AUTHOR]