Study on Mineral Metabolism of Dairy Cows
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Macrominerals as well as trace elements take part in important processes in the body and have regulative functions. Sodium, potassium and chlorine keep the cation-anion equilibrium in in balance, calcium builds up the bones and is needed for milk production, phosphate can be found in all cell types and is in duty to transfer energy and magnesium is needed for nerve and muscle irritability. Their deficiencies can lead to severe diseases like milk fever or tetany. On the other hand an excess concentration can harm the animals, too. Too high potassium levels impair the calcium mobilization and contribute to milk fever due to this. Microminerals such as selenium, zinc, copper and manganese support the immune functions, anti-oxidative processes, keratinization of the teat canal and claw horn and reproductive performance. Deprivation of them increases the risk of reproductive problems, infectious diseases like mastitis and bad claw integrity. On the opposite excess amount dietary copper supplemented over a long period can lead to chronic copper toxicosis. In this study blood, urine and hair samples were taken from Holstein-Frisian cows in a large scale farm in the middle of Hungary. The cows were divided into 6 groups – 1) close up cows 14 days before parturition, 2) fresh cows up to 7 days after parturition, 3) primiparous cows 8-30 days in milking (DIM), 4) multiparous cows 8-30 DIM, 5) primiparous cows 60-100 DIM and 6) multiparous cows 60-100 DIM. Results of blood and urine analysis were available for all 6 groups whereas hair samples were only obtained for one cow in the close up group and the groups with the fresh cows, the multiparous cows 8-30 DIM and the primiparous cows 60-100 DIM. The two most important results were deficient manganese concentrations in the hair samples and excess copper levels after hair and blood analysis. Manganese deficiency contributes to reproductive failure as it accumulates in reproductive organs and tissues. Increased copper levels indicate too high dietary copper content. As the average hair analysis values of the groups are increased up to 5 times and hair samples present the mineral state 2 to 3 months before the sampling the results indicate excessive Cu supplementation over a longer period. This dietary Cu management can lead to chronic copper toxicosis which can result in death in severe cases. To avoid the above described problems dietary manganese content should be 30mg/kg and copper dietary content should be 10mg/kg on dry matter basis per animal and day.