Sow Contact Is a Major Driver in the Development of the Nasal Microbiota of Piglets.

The nasal microbiota composition is associated with the health status of piglets. Sow-contact in early life is one of the factors influencing the microbial composition in piglets; however, its impact has never been assessed in the nasal microbiota of piglets reared in controlled environmental conditions. Nasal microbiota of weaning piglets in high-biosecurity facilities with different time of contact with their sows (no contact after farrowing, contact limited to few hours or normal contact until weaning at three weeks) was unveiled by 16S rRNA gene sequencing. Contact with sows demonstrated to be a major factor affecting the nasal microbial composition of the piglets. The nasal microbiota of piglets that had contact with sows until weaning, but were reared in high biosecurity facilities, was richer and more similar to the previously described healthy nasal microbiota from conventional farm piglets. On the other hand, the nasal communities inhabiting piglets with no or limited contact with sows was different and dominated by bacteria not commonly abundant in this body site. Furthermore, the length of sow-piglet contact was also an important variable. In addition, the piglets raised in BSL3 conditions showed an increased richness of low-abundant species in the nasal microbiota. Artificially rearing in high biosecurity facilities without the contact of sows as a source of nasal colonizers had dramatic impacts on the nasal microbiota of weaning piglets and may introduce significant bias into animal research under these conditions.