Effect of Two Different Minimum Ventilation Systems on the Thermal Comfort and Productive Performance of Broiler Chickens in Winter Conditions

The typical Brazilian poultry facilities are open and without thermal insulation, making it difficult to maintain building temperature as warm as necessary for the birds in their first week of brooding. This problem increases in the winter because of the difficulty to guarantee adequate minimum ventilation. This research was conducted with broiler chickens, and compared two different types of minimum ventilation systems: negative pressure (NPS) and positive pressure (PPS). The study was done during the winter season in the south of Brazil at integrated commercial avian farms during two flocks. The air temperature and relative humidity, the black globe humidity index (BGHI), and the litter surface temperatures were evaluated and related with the animal performance. Based on the results of the study, it was observed that during the first and second week of brooding, the relative humidity of both treatments provided ideal levels for the comfort of the birds. The daytime BGHI values were similar; however, they were always superior in the NPS, with the greater range during the second week. The litter surface temperature was slightly higher in the PPS. The best poultry production performance results (live weight and feed conversion) were for PPS. The mortality was greater for the NPS. The two treatments yielded final productivity within the satisfactory range according to the national poultry production. The results show that both minimum ventilation systems would be possible to be used in Brazilian conditions.