| Air pollutants emitted from poultry farming,in particular bioaerosols containing large amounts of particulate matter and micro-organisms,are of concern due to their potential negative effects on animal and human health and the environment.High concentrations of bioaerosols can lead to immunosuppression and increased susceptibility to disease,which can significantly affect broiler performance.Among them,fine particulate matter（PM2.5）with aerodynamic diameter less than 2.5μm has a slow settling speed and long spreading distance.It can be deposited deeply in bronchi and alveoli,which is especially harmful to organisms.PM2.5 exposure can induce oxidative stress,inflammatory reaction,cell apoptosis,respiratory system,immune system,cardiovascular system and other systemic tissue damage.This study evaluated the environmental quality and biological aerosols of two different model broiler farms located in Shanxi and Hebei provinces of China.There are two main broiler production systems in China,the three-layer cage house（CH）and the flat net rearing houses（FH）.A 2030 ambient air particulate sampler was used to collect fine particles.Bacterial diversity and relative abundance were analyzed using 16S r RNA sequencing to elucidate bioaerosol variations under different aquaculture patterns.PM2.5 in CH ranged from 174.68 to 412.60μg/m3.the concentrations of PM2.5 in FH ranged from 550.49 to 1160.57μg/m3,respectively.The concentration of TSP（Total Suspended particles）was509.41 to 1367.43 and FH is 1874.56 to 3805.47μg/m3,which are lower than GB3095-1995"Ambient Air Quality Standard"designated safe value 8mg/m3.NH3 concentrations in CH and FH were 6.28 and10.45 ppm,respectively in the early stage,1.96and 11.38in the middle and 0 and 9.41 ppm in the late stage.A significant average difference was observed at end of the 6th week for weight gain,FCR and survival rate between the two models.The average concentrations of metal elements in PM2.5（Mg,Fe,Ba,Ca,Zn,K,Al,Na）are 5.43,1.96,21.51,19.61,39.40,29.45,33.37,and 111.68μg/m3.The average concentrations of the metals elements in TSP（Mg,Fe,Ba,Ca,Zn,K,Al,Na）are 13.38,6.90,4.15,32.08,41.18,54.72,38.74,and 126.36μg/m3 respectively.The average concentrations of water-soluble ions in PM2.5(F-,Cl-,NO3-,SO42-,Na+,K+,Mg2+,Ca2+,NH4+)are 0.36,4.57,6.00,11.48,2.66,4.15,0.96,2.24,and 4.15μg/m3.The average concentrations of water-soluble ions in TSP(F-,Cl-,NO3-,SO42-,Na+,K+,Mg2+,Ca2+,NH4+)are 3.00,15.93,15.13,32.98,7.94,25.85,6.46,13.10,and 8.64μg/m3.The results of 16S r RNA high-throughput sequencing showed that the bacterial species of CH and FH were very similar in indoor environment,but there were many unique bacterial species outside.The10 most abundant genera in PM2.5 are Rothia,Lactobacillus,Ruminococcus,Macrococcus,unclassified f＿Lachospiraceae,Faecalibacterium,Enterococcuss,Blautia,Acinetobacter and Corynebacterium.Association analysis of environmental factors showed that bacterial community structure was mainly affected by temperature and humidity.Interestingly,the bacterial community structure of the FH24group was significantly different from that of the other groups,showing more influence by CO2,NH3and PM2.5 factors.It is suggested that high PM2.5 level is another main factor that leads to the change of indoor bacterial community structure,and improving indoor ventilation can effectively eliminate this factor.In a word,this study systematically explored the environmental factors and bacterial aerosol changes in the complete growth cycle of broilers in the models of cage and flat-net rearing,which provided theoretical basis for strengthening the prevention and control of bacterial aerosol in broiler breeding industry and improving environmental control technology.It will provide reference for preventing and controlling the health hazards of bioaerosol,and provide theoretical basis for improving environmental control level and promoting healthy breeding. |
PDF Full Text Request