Fate of Conjugated and Free Estrogens in Swine Manure Collected from areas Housing Piglets, Pregnant Sows and Finisher Pigs

Abstract

Occurrence and fate of estrogens and their metabolites were studied in pig manure collected during winter and summer seasons from sites housing piglets (Nursery (Nur)-manure), pregnant and nursing sows (PS manure) and finisher pigs (FPig manure). The liquid and solid fractions of manure were analyzed for (1) total solids (TS), volatile solids (VS) and total organic carbon (TOC), (2) E coli and M fujisawaense enumeration, (3) total and individual estrogens and (4) estrogenic activity.  This study showed that VS and OC values, E coli and M fujisawaense enumerations, estrogen concentrations and estrogenic activity exhibited the following pattern: Nur-manure << FPig-manure < PS-manure. The values for summer and winter Nur-manure did not differ significantly, while the values in summer PS-manure or FPig manure samples were significantly higher than values in corresponding winter samples. Although, estrogens distributed between liquid and solid fractions of manure, concentrations of free, but not conjugated, estrogens depended on manures’ TOC values: an increase in TOC associated with an increase in free estrogen concentrations in liquid manure. However, an increase in TOC decreased the bacterial population in manure liquid by increasing their translocation from liquid into the in solids and ensuing bacterial stabilization. This may increase estrogens’ deconjugation and/or degradation. Estrone (E1) sulfate (sE1), free E1 (fE1), E1 glucuronide (gE1) and E1 metabolites were major steroids present in Nur- and PS-manure, while fE2 and gE2 were predominant estrogens in FPig-manure. In total, the winter estrogen load in liquid was 5.1 mg/L and the load in solid was 4.93 mg/kg. Assuming that 2.3 x 10⁸ kg of manure is produced in the USA per day, approximate hormone load will be 2.3 tons/day. However, manure contains microorganisms that hydrolyze estrogens, thus actual hormone load will be considerably lower.