Analysis of environmental conditions and management in a compost-bedded pack barn with tunnel ventilation

The housing system based on compost-bedded pack for dairy cows is spreading rapidly in Brazil. Completely open buildings without curtains and simple roofs are usually provided. However, in the last years some new completely closed barns have been realized. This study aims to analyse one of these closed barns, located in the State of Minas Gerais. The two main sides of the facility are provided with polyethylene curtains of blue colour and five deflectors. The barn is equipped with an evaporative adiabatic cooling system, associated with the tunnel-style ventilation, realized with exhaust fans, continuously operating 24 hours a day. 85 lactating Holstein cows were housed in the barn during the trials carried out in the winter season 2019. Microclimatic data were collected continuously. Air speed, illuminance and bedding temperature were measured during the farm visits. Pack moisture was calculated. The results state the importance of bedding management and climatic conditions inside the barn. It emerges that the cows housed in this kind of closed barn, with forced ventilation, are in good thermal conditions, which are fairly constant. The average illumination of the barn can be considered acceptable (55.06 lx), even if some areas of the barn present values below the minimum ones reported in literature. The bedding temperature varies between a maximum of 36.33 °C and a minimum of 25.44 °C with an average of 31.26 °C. The values of bedding moisture are between a maximum of 64.36% and a minimum of 60.81% with an average of 62.48%.