The impact of host genetics on porcine gut microbiota composition excluding maternal and postnatal environmental influences.

The gut microbiota of the pig is being increasingly studied due to its implications for host homeostasis and the importance of the pig as a meat source and biomedical model of human diseases. However, most studies comparing the microbiome between different breeds do not consider the influence of maternal environment during the colonization of the microbiota. The aim of the present study was to compare the gut microbiota during postnatal growth between two pig genotypes (purebred Iberian vs. crossbreds Iberian x Large White pigs), gestated in a single maternal environment (pure Iberian mothers) inseminated with heterospermic semen. Postnatally, piglets were maintained in the same environmental conditions, and their microbiota was studied at 60 and 210 days old. Results showed that age had the greatest influence on alpha and beta diversity, and genotype also affected beta diversity at both ages. There were differences in the microbiome profile between genotypes at the ASV and genus levels when jointly analyzing the total number of samples, which may help to explain phenotypical differences. When each time-point was analyzed individually, there were more differences at 210 days-old than 60 days-old. Fecal short-chain fatty acids (SCFA) were also affected by age, but not by genotype. These results may be a basis for further research on host genotype interactions with the gut microbiota.