Seasonal dynamics of cow milk mineral composition and its dependence on the use of sorbent under radioactive contamination of the territory

The quantitative composition of biogenic macro- and microelements of milk is known to be closely connected with the chemical composition and environmental pollution of fodders by heavy metals. During grazing and stabling periods we examined feeds and milk from milk cows on private farms within Bryansk Province (Klintsovskii and Novozybkovskii regions, 2004-2007) contaminated by 137Cs (670-1010 kBq/m 2) after the Chernobyl accident. During the monitoring all animals received a specific enzyme, ferrocyn, which provided effective decrease in milk contamination by 137Cs, at a daily dose of 6 g/head for 4 years. The absence was shown of critical concentrations of heavy metals in milk in radiocesium comtaminated areas in the Bryansk region. Quantitative variations in the composition of macro- and microelements in milk were connected with the diet mineral composition and physiological condition of cattle. The reasons for variations in the mineral metabolism of tested cows were mainly the species composition of vegetation and the condition of local plots in the spring-autumn period, as well as non-certified components of the ration in the indoor period. The levels of chemical elements decreased or increased slightly in the milk which was less contaminated with 137Cs, except Co and Al, which increased 1.8 and 1.5 times, respectively (0.14-0.23 mg/l). Salting on private farms did not always meet the requirements. The existing Co deficit in pasture fodder in the region needed a relevant correction by mineral additives. The use of ferrocyn did not have a noticeable influence on mineral metabolism in animals, but reduced the 137Cs level in milk from 680 to 95 Bq/l, if the pastures less polluted with 137Cs were also used. Overall, our data on mineral metabolism and milk composition in areas affected by significant radioactive contamination after the Chernobyl accident showed the effectiveness of countermeasures applied in the region.