Reference intervals for trace minerals and heavy metals in livers of cattle in wilderness areas in the Netherlands

We examined the liver mineral concentrations of semi-wild cattle breeds (Highland, Galloway, Rode Geus) grazing in natural or near-natural flood-prone areas in the Netherlands. These breeds are employed as part of trophic rewilding initiatives aimed at maintaining biodiverse ecosystems through natural grazing patterns. Our primary goal was to derive RIs for liver mineral concentrations for these cattle populations. We collected and analyzed liver samples from 96 cattle from 14 sites in the Netherlands and used inductively coupled plasma mass spectrometry to measure concentrations of trace elements and heavy metals, including arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, vanadium, and zinc. The statistical analysis included Pearson product moment correlations and k-means clustering to evaluate patterns within the data. The highest significant correlations were between liver cadmium concentrations and animal age, and between liver copper and selenium concentrations. Breed-related differences were found for liver cadmium and molybdenum concentrations, but we could not isolate breed-differences in forage selection from environmental variables such as soil composition. Liver copper levels in many animals were below thresholds typically used to indicate copper deficiency in farmed cattle.