"Investigations of mineral- (Ca, Mg, S) and trace element-concentrations (Cu, Zn, Se, Fe, Mn, Co) in cattle in different sample media with special consideration of liver biopsies" The monitoring of mineral- and trace element-supply should be integrated into the stock management of the dairy herds. Unspecific symptoms such as reduced fertility, growth and performance depressions can be the result of imbalances in mineral balance. However, these are always only suspected diagnoses if no suitable diagnostics are initiated. Choosing the right sample medium is essential in order to be able to make the most accurate statement on the supply status. The aim of this study is to examine and assess liver as a test medium for evaluating the mineral- and trace element-supply in dairy cattle. For this purpose, hepatic concentrations are compared with other media. The suitability of the different substrates for the respective element is then assessed in order to provide information about the supply situation. Therefore, many samples were collected over a period of two years in Brandenburg, Saxony, Saxony-Anhalt, Thuringia and Mecklenburg-Western Pomerania. Sample materials consisted of blood, faeces, liver, hair and feed. The data includes 355 individual and 30 pool samples from clinically healthy Holstein Frisian. The sample values for media faeces, urine, whole blood, animal feed and hair are made up of pooled samples from 10 tested animals. A feed analysis was carried out for the TMR and concentrations of bulk elements calcium, magnesium, sulfur. The trace elements copper, zinc, selenium, iron, manganese and cobalt were determined using ICP-OES and ICP-MS. For the elements magnesium, copper, zinc, selenium, iron, manganese und cobalt, the group of calves differs significantly from the studied groups of lactating and non-lactating cows. This is of particular importance as there is little literature to assess concentrations in calves. For the elements calcium, magnesium and sulfur, the content in the liver can only be used to a limited extent to assess the metabolic supply situation, so that the liver biopsy does not bring any added value. A more reliable interpretation can be achieved by evaluating and combining it with other substrates or blood values. For copper, liver biopsy is the method of choice for assessing the metabolic supply situation, but should be supplemented by the analysis of TMR and feces for the nutritional supply situation to account for the antagonists. Zinc shows a very high liver concentration, especially in calves. Therefore, the biopsy is the best diagnostic tool for metabolic medium-term care. For selenium, the liver is a similarly sensitive medium as blood. In the context of the biopsy, a good statement can be made about the current supply situation by measuring the concentration, but it does not bring any added value. Iron can be measured in high concentrations in the liver, especially in calves. In adult cattle, the biopsy is a diagnostic if the TMR has too low an iron content. The result of the iron concentration in the liver biopsy is falsified by the probe`s own blood content, so that a statement is unclear and requires further investigations. For the medium of manganese, liver biopsy is the diagnostic of choice, especially when it comes to intoxication. However, due to the limited data available, the assessment of liver manganese can only be evaluated to a limited extent and requires further analyses. Liver tissue reflects the most accurate result of cobalt concentration. Higher concentrations could be measured in these samples than in the other media examined, which improves an assessment of the metabolic supply situation. Further investigations are recommended to substantiate the values determined here. This then forms the basis for the development of monitoring profile of the metabolic supply situation in juvenile and adult cattle. In this study, reference ranges for the individual elements in the liver tissue could be determined. The following table summarizes values in mg/kg for the three groups studied. Concentrations of the individual elements in the liver tissue for the groups studied in mg/kg TS: I = Calf, II = lactating, III = non-lactating Selenium: I: 0,9 – 1,1 | II: 2,0 – 2,3 | III: 1,3 – 1,7 Manganese: I: 4,95 – 6,2 | II: 10,2 – 10,6 | III: 7,6 – 8,4 Cobalt: I: 0,08 – 0,12 | II: 0,26 – 0,28 | III: 0,2 – 0,24 Iron: I: 466 – 731 | II: 273 – 303 | III: 314 – 405 Zinc: I: 243 – 360 | II: 99 – 112 | III: 106 – 112 Copper: I: 153 – 203 | II: 482 – 526 | III: 241 – 326 Calcium: I: 199 – 312 | II: 251 – 317 | III: 229 – 259 Magnesium: I: 646 – 802 | II: 636 – 688 | III: 661 – 685 Sulfur: I: 8202 – 9557 | II: 8153 – 9046 | III: 8146 – 8461
