The content of ten elements in pig feed and manure and its relationshipwith element concentration in earthworms on swine farms

The aim of this investigation is to determine the content of ten elements, Cr, Mn, Co, Ni, Fe, Zn, As, Cu, Se, and Cd, in pig feed, manure and earthworms (Lumbricus terrestris). Samples were collected during 2015 and 2017, on four pig farms in Serbia, and analyzed for elements by inductively coupled plasma mass spectrometry. According to the mean concentrations, the elements show the following trends: Fe > Mn > Zn > Cr > Ni > Cu > Cd > Se > As > Co in monocalcium phosphate, Zn > Mn > Fe > Cu > Co > Cr > Ni > Se > As > Cd in vitamin-mineral premixes, Fe > Zn > Mn > Cu > Ni > Cr > Se > Co > As > Cd in complete feed, and Fe > Zn > Mn > Cu > Ni > Cr > Co > Se > Cd > As in pig manure. The obtained results show that monocalcium phosphate and vitamin-mineral premixes are the main source of Mn, Zn, and Fe in complete feed mixtures. The Cd concentration in one sample of monocalcium phosphate exceeds the maximum permissible level. Only one out of six investigated complete feed mixtures was in accordance with the national and EU regulations. The presence of Fe, Zn, and Mn in earthworms reflects their concentration in pig manure, but this is not noticed for Cr, Cu, Se, As, Ni, Co, and Cd.