Spatial distribution of bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn with a negative tunnel ventilation system

This research aimed to characterize, evaluate and compare the spatial distribution of the leading bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn (CBP) with a negative ventilation system in tunnel, during summer and winter. The study was carried out in a CBP, located in the Zona da Mata region, MG, Brazil. The geostatistical modeling technique evaluated the variables temperature, moisture content, and pH (on the surface and depth of 0.20m) across the length of the bed. Besides, bed samples were characterized for Carbon (C), Nitrogen (N), and C:N. Cows housed in the CBP were assessed for locomotion and hygiene score and average milk production. To evaluate the thermoregulation of the cows, the respiratory rate (RR) and surface temperature (ST) were measured. The geostatistical analysis showed spatial dependence and the non-uniformity of the spatial distribution of bed variables. The worst levels of the bed's temperature and moisture were found in the regions close to the evaporative cooling plate, surrounding the feeding alley, and in the region with the highest cow stocking. The C:N ratio, obtained in both climatic seasons of the year, remained outside the recommended range for ideal composting. During the summer and winter, the bed variables' values suggest that the material was below levels for optimal composting; however, the aerated inner layer was biologically active. The high animal density significantly impacted the worsening of the bed's moisture content and internal temperature. In general, dairy cows showed adequate hygiene (score 1 and 2) and locomotion (score 0 and 1) scores for the two climatic seasons evaluated, indicating good welfare conditions. In relation to RR and ST, the summer period presented less favorable environmental conditions. During winter, the average milk production was 28.1 ± 7.2kg day-1, and during summer, it was 26.9 ± 6.7kg day-1.