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The diagnosis of a demand-covering mineral supply is significant for the herd health and thus for the integrated livestock management. Urine reflects a current mineral supply situation, as an important way of mineral excretion. Urine should be used in addition to other substrates such as blood.
The aim of this work was, to give an overview of the function, deficiency, toxicity, homeostasis and diagnostics of minerals and to develop reference ranges for minerals and trace elements in urine.
Therefor urine pool samples were taken from different dairy farms in northern Germany for several years. The pooled samples were collected from 7-10 clinically healthy Holstein Friesian cows from the lactating groups: preparer (3-0 weeks a.p.), fresh dairy cow (0-1 week p.p.) high lactation (3-5 weeks p.p.), late lactation (15-18 weeks p.p.) and dry standing cows (to 3 weeks a.p.). In urine, the minerals and trace elements (K, Na, Mg, Ca, Cl, P, S, Cu, Se, Fe, Mn, Mo, Cr, Co, Cd, Al, Pb, Sr) were determined by ICP-OES.
In this study, reference ranges for the individual elements could be determined. Due to the significant differences in the dynamics of lactation the fresh dairy cows have been excluded from consideration in almost all minerals for the reference values are not distorted by the calving-related features in the homeostase of minerals. It was also found that for some elements, such as iron, manganese and molybdenum the content in the urine can be used only conditionally to assess the supply situation. Therefore, always blood values and other substrates such as foraging or hepatic tissue should be included in the analysis, to ensure an optimal interpretation of the supply situation.