Macro- and microelements in milk and hair of cows from conventional vs. organic farms

Considered were four dairy farms. Two were certified organic farms and two were conventional – one with intensive and one with extensive production system. Observations were conducted on 10 Holstein-Friesian (HF) cows from each farm while from conventional farm with extensive production additional 10 Polish Red (PR) cows were observed. Samples of milk and hair for determination of minerals were collected in September. Hair samples were taken from the poll. Twenty-nine elements – Ca, K, Mg, Na, P, S, B, Ba, Co, Cr, Cu, Fe, Ge, I, Li, Mn, Mo, Ni, Se, Si, Sn, Sr, V, Zn, Al, As, Cd, Hg, and Pb – were determined in milk and hair. The concentrations of Ca, Mg and P in milk were highest in intensive production system with no grazing, compared with conventional and both ecological farms with pasture feeding. The highest concentrations of I, Mn, Sr, V, and Zn in milk were found on conventional intensively producing farm, while those of Li, Si, Sn, Ba, and Ge on both organic farms. The highest concentrations of B, Be, Co, Fe, Ge, and Li in cow hair were found on organic farm, and highest concentration of Cr, I, Mo, Se, Sn, Sr, V, and Zn on conventional farm with extensive production. The highest levels of Cd and Pb in milk were found on conventional farm with extensive production. Generally, the levels of all toxic elements in milk appeared low and below admissible. The results presented suggest that the mineral composition of cow milk and hair depended on production system followed on the farm.