Status of selenium and vitamin E on Norwegian organic sheep and dairy cattle farms

Summary

Herbage selenium (Se) concentration is generally low in Norway. It is unknown, if feeding practises on Norwegian organic farms fulfil the dietary need of Se and vitamin E to sheep and dairy cattle. Therefore, we analysed Se in soil and herbage, and Se and vitamin E in animal blood in the indoor feeding season at 14 organic dairy and 14 organic sheep farms. The herbage Se concentration was low. Approximately 50 and 35 % of all samples in the first and second cut, respectively, had Se concentrations below the detection limit of 0.01 mg/kg dry matter (DM). The median (10th, 90th percentile) Se concentrations were <0.01 (<0.01, 0.03) and 0.02 (<0.01, 0.06) mg/kg DM in the first and second cuts, respectively. Whole blood Se concentrations were 0.10 (0.04, 0.15) µg/g in dairy cattle and 0.14 (0.03, 0.26) µg/g in sheep. Vitamin E concentrations were 4.2 (2.7, 8.4) mg/L in dairy cattle and 1.3 (0.9, 2.4) mg/L in sheep. None of the soil or plant variables explained the variation in herbage Se concentration, although Se in soil and plant tended to be correlated. Herbage Se concentration was inadequate to meet the dietary Se requirements. Vitamin E requirement was only met in dairy herds. We recommend Se and vitamin E supplementation to ruminants on organic farms.