Rethinking environment control strategy of confined animal housing systems through precision livestock farming

Climate represents one of the main limiting factors of production efficiency. Thermal stress events can cause reduced performance, morbidity, and mortality, resulting in significant economic losses and animal welfare concerns. Environment control in confined animal housing systems is typically based on heat and moisture production rates at predetermined ambient temperature levels measured between 1950 and 1980. This traditional control method can fall short in meeting the true thermal needs of the animals since it does not account for factors now acknowledged as affecting the animal's productive responses to surrounding conditions, such as humidity, drafts, radiation, physiological state, and social interactions. Also, advancements in animal genetics, nutrition, and management practices have led to considerable changes in sensible and latent heat loads of modern livestock buildings. In this context, precision livestock farming technologies (sensors, detectors, cameras, microphones, etc.), enabling the automatic monitoring of environmental, physiological, and behavioural variables, can be used to continuously assess livestock performance and well-being in relation to their environment. An innovative strategy for environment control of livestock buildings could include the analysis of: (i) heat and moisture production rates using the most recent bioenergetic models; (ii) thermal stress through multi-factor animal comfort indices based on some environmental and physiological measurements; and (iii) animal behaviour as a response to changing environmental conditions. This paper presents a critical review of the state of the art of precision environment control of livestock buildings, identifying knowledge gaps, research opportunities, and technical challenges.