Foetal Calf Microbiome

Sterility until parturition has been extensively debated due to reports of microorganisms in proximity to the foetus during pregnancy but concerns about contamination. We investigated the presence of a microbiome in the foetal gastrointestinal tract (GIT) of calves at 5, 6, and 7 months gestation. Five components of the GIT (ruminal fluid, ruminal tissue, caecal fluid, caecal tissue, and meconium) and the amniotic fluid were found to contain distinct bacterial and archaeal communities. Viable representative bacterial cultures could be isolated from these communities from 5 months gestation. Bacterial diversity differed between compartments with dominant phyla in the amniotic fluid and those in the caecal fluid and meconium. Bacterial and archeal abundances associated with the ruminal tissue were lower than the other compartments. Here we demonstrate that the foetal GIT is not sterile and that it is spatially colonized prior to birth by a pioneer microbiome