Trace and macro element evaluation in blood, diet and milk and their interrelationships in Holstein dairy cows

Micro and macro-mineral concentrations in serum, milk and diet were investigated in 70 dairy cows, calved up to 4 calving and pregnant less than 7 months to determine the mineral status, their interrelationships and the main indices used in prediction of necessary minerals. Five ml of Jugular blood, 10 ml of milk and 25 gr from each alfalfa and concentrate were prepared and analysed for trace and macro elements in clinical pathology and food analysis laboratories. Mean serum Mn and Fe were low while others in serum, milk and diet were in normal range. With the exception of serum Fe, milk Mn and Cu, mean serum, milk and dietary elements were significantly different among herds. Various relationships were observed among elements with the greatest in serum Mo, Mn, Fe, P, milk Mn, Ca, Na and Ca, P in diet. Correlations among serum elements were greater than in milk and diet. The relationships among serum trace elements were higher than macro-minerals, whereas correlations among macro-minerals were higher in milk than in serum and diet. There were correlations between DMg/SFe, DMg/SP, DMg/MCu, DFe/MCa, DCu/MCu, DK/MMn. Dietary Mg and milk Cu showed the greatest correlations with others in diet and milk. The regression equations were found between serum Mn and Mo with serum Fe, Cu, Ca and P while not be seen in milk and dietary elements. In conclusion, serum Mn, Fe and Cu in Urmia cows were partially low whereas others not. Serum Mn, Mo, Ca and P are more reliable elements due to their relationships with minerals in serum. Serum Mn and Mo showed the equations with the minerals in serum, and are used as indices in prediction of the elements necessary in cows. To increase milk production and avoid any mineral deficiencies, supplementation of Mn and Fe are recommended in cows’ nutrition.