To date, studies on the swine gut microbiome have focused almost exclusively on bacteria. Despite recent advances in the understanding of the swine gut bacteriome at different growth stages, a comprehensive longitudinal study of the lifetime dynamics of the swine gut virome is lacking. Here, we used metagenomic sequencing combined with bioinformatic analysis techniques to characterize the gut viromes of parental-generation and offspring pigs at different biological classification levels. We collected 54 fecal samples from 36 parental-generation pigs (18 breeding boars [Duroc] and 18 pregnant/lactating sows [Landrace]) and 108 fecal samples from 18 offspring pigs during the lactation (day 3), nursery (days 26, 35, and 49), growing (day 120), and finishing (day 180) stages. Alpha diversity, including community richness (richness index) and diversity (Shannon index), showed an overall increasing trend in offspring pigs. Distinct shifts (beta diversity) in the microbiome structure along different growth stages were observed. The linear discriminant analysis effect size (LEfSe) algorithm revealed 53 viral genus that are stage specific. Host prediction results showed that enteric viruses are probably correlated with carbohydrate decomposition. We identified abundant auxiliary carbohydrate-active enzyme (CAZyme) genes from enteric viruses, most of which are glycoside hydrolase genes and participate in the biolysis of complex polysaccharides. IMPORTANCE This study shows that distinct stage-associated swine gut viromes may be determined by age and/or gut physiology at different growth stages, and enteric viruses probably manipulate carbohydrate decomposition by abundant glycoside hydrolases. These findings fill a gap in the longitudinal pattern of the swine gut virome and lay the foundation for research on the function of swine enteric viruses.
Keywords: auxiliary metabolic genes; dynamics; metagenome; swine gut virome.