Comparative analysis of performance by cows confined in different typologies of compost barns

The compost barn system was designed to be a sustainable alternative housing system for dairy cows. In order to help producers in the region to choose the best type of facility from the point of view of the milk production of the animals, this study compared the productivity of cows confined in an open composting barn with natural ventilation and in a closed composting barn with negative pressure ventilation and evaporative cooling panels. The temperature and relative humidity of the air were monitored, as well as the milk production of the animals housed in the facilities, and THI (Temperature and Humidity Index) were calculated. During the trials, the maximum daily temperatures of the air reached values around 27 °C and the THI remained within the normal range of up to 70. The average productivity remained in the general pattern described in the literature from 23 to 44 kg of milk cow-1 day-1, with lower rates obtained in the closed house. As the variation of the index used to describe the internal environment was not significant, it can be inferred that climatic elements as temperature and air humidity, under the conditions analyzed were not the main factors influencing the productivity rates of dairy cattle. In conclusion, under the analysed conditions the use of a closed barn with negative pressure ventilation is hardly justified as a plant that favoured the productivity of the confined cows.