Characterization and quantification of antibiotic resistance genes in manure of piglets and adult pigs fed on different diets

- Feed significantly increased ARGs and transposon genes in the pig manure.
- The ARG diversity was higher in manure of piglets than in that of adult pigs.
- ARG diversity correlated positively with the concentrations of antibiotics and heavy metals.

Studies have shown that pig manure is a reservoir of antibiotic resistance genes (ARGs). However, little is known about the characteristics of ARGs in the manure of piglets and adult pigs fed on different diets. In the present study, the ARG characteristics of the manure of piglets and adult pigs fed on different diets (feed, grain) were analyzed using high-throughput fluorescence quantitative PCR. Correlations between heavy metals, antibiotics, and ARGs in pig manure were analyzed. The results showed that the heavy metal and antibiotic contents in the manure of pigs receiving feed significantly exceeded those in the manure of pigs receiving grain. The heavy metal and antibiotic contents were higher in manure of piglets than in that of adult pigs. Feed significantly increased the ARG diversity in the pig manure. The ARG diversity was higher in manure of piglets than in that of adult pigs. In the manure of pigs receiving feed, 25 (from piglets), 12 (from adult pigs) ARGs were enriched significantly compared with pig fed with grain. In particular, sat4 (in piglets) and vatE-01 (in adult pigs) showed the highest enrichment, being increased by 59 and 19-fold, respectively. The ARG diversity correlated positively with the concentrations of antibiotics and heavy metals in the manure.

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