Ratio of selenium concentrations between soil, forage plants and blood serum of beef cattle studied in organic and conventional farms.

The aim of the study was to compare the selenium (Se) status of beef cattle from conventional farms with the status of cattle from organic farms located in western Pomerania and to determine the ratios of Se concentration between soil, forage plants and animals at these locations. The mean total Se (Se_T) content in soil was 0.208 mg/kg dry matter (DM) on organic farms and 0.254 mg/kg DM on conventional farms. Animals from conventional farms had significantly (p < 0.05) higher serum Se concentration than those on organic farms. As Se deficiency were classified in 75% of animals from organic farms and in 42% animals from conventional farms. A lack of Se supplementation is associated with a serious risk of deficiency in ruminants, particularly in areas with low Se levels in the soil-plant system. Therefore, more attention should be devoted to increasing the bioavailability of Se for plants by enhancing the physicochemical properties of soil. In addition, the composition of swards for grazing should be adjusted to increase the share of forage plants capable of collecting larger amounts of Se from soil.