Automated climate control to reduce leg disorders in broilers farming

Objectives. Good environmental conditions allow maintaining good levels of productivity and animal welfare in broiler houses. Indeed, being the broiler house a closed environment, all the variables involved must be carefully controlled and regulated. Broilers are the fastest-growing and cheapest sources of animal protein among farmed species; their performance is heavily conditioned by environmental parameters such as indoor air temperature, relative humidity, and ventilation speed. A good climate manager could be evaluated through the ability of the ventilation system to control air temperature, relative humidity and air speed at animal height to maintain tolerable concentrations of gases, dust and airborne microorganisms. The wrong management of those parameters may result in poor litter quality with a direct effect on broiler welfare. Genetic selection for fast growth is known to be influential on leg disorders (footpad dermatitis (FPD) and lameness (LMNS)) but several studies linked them to poor environmental conditions. Ulcers that arise from advanced lesions can negatively affect the walking ability of the birds, with significant effects on both animal welfare and economic aspects in intensive broiler farming. Due to the strong connection between leg disorders, litter quality and thermal comfort, the aim of this study was to find the association between environmental predisposing factors, measured in continuous (such as air temperature and relative humidity) and leg problems, manually scored during the welfare assessment procedure, to develop an automated climate control system to reduce lesions. Methods. In this study, the welfare of the chickens was assessed manually three times per production cycle (at week 3, 4 and 5), scoring footpad dermatitis, lameness, and litter quality. In the same broiler farms, variables such as air temperature and relative humidity were automatically measured over the same period. These variables were combined into a thermal comfort index and associated to upper and lower thresholds, which made it possible to quantify the percentage of time the birds spent out of the thermal comfort zone (POOC). The data was analyzed by combining data from the welfare assessments with environmental data collected by the automated monitoring systems. Results. The analysis showed that footpad dermatitis and lameness were more frequent when the flock was exposed to poor environmental conditions for prolonged periods (P< 0.001). The potential association between automated control of the environmental conditions and the welfare assessments might be the basis for the development of models and algorithms capable to automatically detect thresholds above which lesions are mostly probable.