Abstract: 【Objective】 This study was aimed to explore the environmental parameters and their distribution pattern under two ventilation modes in large-scale piggery farms of Hangzhou, and screen out the suitable ventilation modes for promotion in this region.【Method】 The fattening houses in Hangzhou with two representative ventilation modes, transverse ventilation and longitudinal ventilation, were selected as the research objects, and the thermal environmental parameters, concentrations of harmful gases at different time points in the morning, noon and evening and at three different locations of the wind inlet, the center of the piggery and the wind outlet were monitored for a week.The effects of different time points and different positions on the thermal environment parameters such as temperature, relative humidity, wind speed, and the concentrations of harmful gases ammonia (NH₃) and hydrogen sulfide (H₂S) were analyzed, and the thermal environment parameters and harmful gases concentrations under the two modes were compared and analyzed.The air precipitation method was used to collect the bacteria in the environment of fattening house, and the bacteria were cultured and statistically analyzed to compare the difference in the number of bacteria in fattening house under the two modes.【Result】 The relative humidity in fattening house under the two ventilation modes were lower than those of the national standard and were less affected by location and time points.The relative humidity of fattening house under longitudinal ventilation mode was significantly higher than that of the transverse ventilation mode (P<0.05).There was no significant difference in the average temperature between the two ventilation modes (P>0.05), and the temperatures of fattening house in the noon were significantly higher than those in the morning and evening (P<0.05).The temperatures in piggery were affected by the location under the longitudinal ventilation mode.The average wind speed of fattening house under the longitudinal ventilation mode was (1.09±0.42) m/s, which was in line with the national standard and extremely significantly higher than that of the transverse ventilation mode (P<0.01).The wind speed in piggery was affected by the location under the ventilation mode, and the time points had little effect on it.The concentrations of harmful gases in the air environment of the pigpen under the two ventilation modes were within the national standard range, but the concentrations of NH₃ and H₂S in the longitudinal ventilation mode were significantly lower than those of the transverse ventilation mode (P<0.05).There were no significant differences in H₂S and NH₃ concentrations at each time points (P>0.05).The distribution of harmful gas concentration was significantly affected by different positions in fattening house, and the concentrations of harmful gases at the wind inlet were significantly lower than those at the center of the piggery and the wind outlet(P<0.05).The total number of bacteria in the air under the longitudinal ventilation mode met the national standard and were significantly lower than those of the transverse ventilation mode (P<0.05).【Conclusion】 The overall environment of fattening house under longitudinal ventilation mode was better than that under transverse ventilation mode.The design of fattening pig house tended to promote the longitudinal ventilation mode.

Key words: ventilation modes; thermal environment of piggery; harmful gas; microbes; difference analysis