| The swinery health is closely related to their feeding environment, indoor air is an important part of the pig house environment, its quality has direct influence on epidemic prevention, swinery healthy and pork quality. While the quality of indoor atmosphere in pig house has been declining, the harmful gas, dust and microbial aerosol to increase which has a significant impact on the performance, growth and development of piglets, even cause epidemic disease to erupt, all this have posed a huge threat to livestock industry. The present study has been carried out to study spread and purification of harmful substances in pig house.Experiment1:Transmission to the environment of microbiological aerosol in pig housesAir samples, including indoor and outdoor of2pig houses were collected by fallen plate method. The results showed that:(1) The concentrations of microbiological aerosol in pig houses were higher than the outdoor environment.(2) The concentrations of airborne aerobic bacteria in downwind air were closely related to distances to the pig house, the concentrations of microbiological aerosols are relatively higher in the0to30meters downwind. It indicates microbiological aerosols can spread from indoor to outdoor through air exchange. But relatively less over the70meters downwind. Experiment2:Seasonal changes and aerodynamic distribution feature of airborne aerobic bacteria in pig houseIn order to study seasonal changes and aerodynamic distribution feature of airborne aerobic bacteria in pig house. Air samples about airborne aerobic bacteria and airborne E.coli were collected using six-stage Andersen microbial sample in a pig house from January2011to October2011. The results showed that:(1)The concentration of airborne aerobic bacteria in pig house was dynamic which reached summit in winter and bottom in summer.(2). There are almost38.0%airborne aerobic bacteria and43.1%airborne E.coli whose aerodynamic diameters were over5μm can reach the upper respiratory tract of people and pig and will make potential threatening for their health.19.79%airborne aerobic bacteria and22.65%airborne E.coli whose aerodynamic diameters were less than2μm can intrude into alveolus directly and will make severe threatening to stockmen and swinery. Experiment3:The daily change of harmful substances concentration in closed pig houseIn the present study, the concentration of harmful substances whether after running fresh air system or not in closed pig house were measured. The results showed that:(1) The NH3and CO2concentration in closed pig house exhibited obvious daily variation:the peak concentration of NH3was at17:00, and the valley concentration was at9:00; the peak concentration of CO2was at10:00, and the valley concentration was at15:00-17:00.(2) The peak concentration of dust was at9:00-11:00, and the valley concentration was at19:00. The concentration of airborne aerobic bacteria and airborne E.coli both show the same trend, namely stay high level at morning and night while low at noon.(3) The concentrations of airborne aerobic bacteria, airborne E.coli and CO2in closed pig house deduced significantly, the percentages of which were22.96%,50%and11.85%after running fresh air system1hour, The percentages of NH3was31.86%after2hour, dust was72.84%after3hour. Experiment4:Effects of fresh air system on the air quality in the piggery, growth performance and blood biochemical parameters of pigletsThis study was to investigate the effect of fresh air system on air quality in the piggery, growth performance and blood biochemical parameters of piglets. The results showed that:(1) The concentrations of NH3and CO2in closed pig house deduced significantly, the percentages of which were55.23%,33.88%(P<0.01) on0.3m-height layer,27.50%and33.88%(P<0.01) on1.5m-height layer, respectively, compared to with that of the control group.(2) The concentrations of RESP,and TSP in closed pig house reduced, the percentages of which were50.79%and59.58%on 0.3m-height layer,53.06%and65.77%on1.5m-height layer, respectively, compared with that of the control group; The concentration of airborne aerobic bacteria and airborne E.coli in closed pig house deduced significantly, the percentages of which were25.47%,87.5%(P<0.01) on0.3m-height layer,28.47%(P<0.01)and50%(P<0.05) on1.5m-height layer.(3) There were no significant differences on growth performance of piglets by running fresh air system in pig house (P>0.05). Fresh air system group showed higher percentage of peripheral blood CD4+T cells and CD4+CD8+T cells on day14(P<0.05), highly significantly increased the ratio of CD4+/CD8+(P<0.01), decreased significantly the CD8+T cells (P<0.01).In conclusion, this study disclosed the characteristics of the microbial aerosol diffusion, and expounded the seasonal changes and aerodynamic distribution feature of airborne aerobic bacteria in pig house, the daily change of harmful substances in closed pig house and the change of harmful substances in closed pig house after running fresh air system. Running fresh air system in closed pig house has obvious function to advancethe growth, enhance immunity and improve the air quality. |
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