Understanding the microenvironment for dairy cows within an open compost-bedded pack barn in southeastern Brazil: temporal and spatial behaviour during winter and summer

Abstract

Compost-Bedded Pack Barn (CBP) systems, predominantly built and operated in facilities with open sides, have been increasingly used worldwide. These facilities are more exposed to environmental fluctuations; therefore, real-time and spatial mapping of the thermal microenvironment is relevant, as it allows for the identification of areas and times with thermal comfort issues. In this context, the aim of this study was to characterise the temporal and spatial variation of thermal environmental variables (dry-bulb air temperature, relative humidity, and the Temperature–Humidity Index) within an open CBP system during winter and summer using a validated low-cost embedded system (LCES) developed for this purpose. The study was conducted in a typical CBP located in the Zona da Mata, an important dairy basin in Minas Gerais, Brazil's largest milk-producing region. The LCES was developed using low-cost electronic components, calibrated against reference instruments, and employed to monitor the microenvironment in a grid of points distributed throughout the Animal Occupied Zone during winter and summer. Based on temporal analyses, thermal conditions during winter were comfortable for lactating Holstein cows but were stressful in summer (9:10 a.m. to 6:30 p.m.), when there was potential for more efficient use of evaporative cooling (relative humidity ≤ 80.00%). Through spatial analyses, significant spatial variability in thermal conditions was observed, particularly in the morning and afternoon These findings suggest that adjustments to thermal protection systems in CBP facilities are necessary and provide a scientific basis for retrofitting existing facilities and designing new open CBP systems.