Cow Stables Accommodate More Diverse Airborne Bacterial Communities Than Pig Stables.

Abstract

Background A considerable number of research publications indicate that growing up on a farm and possibly also farm exposure in adulthood reduces the risk of asthma and allergies. Contact with livestock, mostly cow and pigs, and increased airborne microbial exposure has been suggested to play a role in this association.Aim This study aims at determining the differences in the composition of the indoor airborne bacterial communities between cow and pig stables as well as between farmers’ and suburban homes.Methods We sampled settled airborne dust using electrostatic dust collectors from Danish cow stables, pig stables, associated farmers’ homes, and from suburban homes and carried out MiSeq sequencing of the V3-V4 region of bacterial 16S rRNA genes isolated from these samples. Results In terms of richness, cow farmer’s homes had the highest bacterial richness followed by cow stables and pig farmers’ homes. All these differences in richness were significant (P < 0.001). Family-level classification showed Staphylococcaceae abundant in cow stables and cow farmer’s homes. Furthermore, specific bacterial taxa that have previously been suggested to contribute asthma protective effects such as Firmicutes and Lactobacillus were more abundant in livestock stables and farmers’ homes than suburban homes. Conclusion People living on farms are exposed to a wider range of microbes and this exposure might contribute to explain the inverse relationship between farm living and asthma risk. Moreover, cow stables harbor a wider range of microbes than pig stables which might provide higher protection towards asthma and atopy. Our finding is in the line with previous epidemiological studies showing that growing up in cattle farms reduces the risk of asthma, hay fever, and atopic sensitization more so than living on the pig farms.