Environmental Air Particulates Monitoring And Distribution Of Microbial Aerosol In Intensive Pig Farms

Livestock farm is one of the main sources of particulate matter(PM)and microbial aerosol in the air environment.The large number of pathogens,such as viruses and bacterium,which are carried by the aerosol in the field of livestock farms are the important factors that cause the occurrence of respiratory diseases both in livestock and poultry workers.As an important way to spread diseases,studies on microbial aerosol has attracted wide attention all over the world in recent years.An intensive pig farm,including the gestation,parturition,nursery and fattening houses in it,was selected to carry out real-time monitoring and collect the environmental microbial aerosol by using TSI laser particle counter,Andersen-6 microbial aerosol sampler and SASS 2300 bio-aerosol sampler.By means of plate counting,extraction of samples DNA,16 S rDNA sequencing and metagenomic sequencing,etc.The particle size and concentration distribution of aerosol particles,the number of culturable bacterium and the original base of pathogens in the air in four different types of pig farms were analyzed.The results show that:The distribution of aerosol particles in the enclosed piggery is affected by animal activity,ventilation system and feeding density: the concentration of aerosol particles in central point was significantly higher than that of the inlet,slightly higher than the outlet;The highest concentration of aerosol particles was found in the parturition which had the highest feeding density among four kinds of pigsty.The concentration of inhalable aerosol particles(0.3-5.0?m)accounted for more than 96% of the total particle concentration,and the particles in this range could reach the deep respiratory tract,causing serious hazard to humans and animals.Among the four kinds of piggery,the highest concentration of culturable bacterium was found in the fattening house with 39.31%~53.84% inhalable percentage.It was positively correlated with the diameter of the samplers.These results showed that there was no correlation between the concentration of culturable bacteria and the concentration of aerosol particles.A total of 91 genera and 158 species of bacterium among the culturable bacterium in piggery were identified by 16 S rDNA sequencing.A total of 234 species of bacterium were identified by metagenome sequencing from the air samples in the piggery,and 35.92% of these species were found in all the four types of piggery.This study will provides basic data for the environmental air quality control in piggery and also the theoretical foundation and technical support for the healthy breeding and safe production of livestock.