RESUMEN
OBJECTIVE: Screening of commercial mineral feeds and mineral licks on the German market containing selenium (Se) in relation to the Se status in equines in Thuringia with different forms of Se supplementation. MATERIAL AND METHODS: Commercially available Se-containing minerals for horses identified by an online research were evaluated for their Se concentration, Se source, flavour carrier and recommended dosage according to the manufacturer's labelling. Furthermore, serum Se status in 8 equine farms was regularly monitored over the period of one year. The sampled horses either received no Se supplement or Se was supplemented by a mineral lick, a mineral feed or supplementary feed. RESULTS: In 29.7 % of the mineral licks, the manufacturers provided a label with information on the maximal daily Se dosage, all of which exceeded the current recommendations of daily Se intake for a 600 kg horse under maintenance conditions. According to the manufacturers' labelled dosage, 67.5 % of the mineral feeds also exceeded the recommended daily Se intake taking the daily Se requirement of a 600 kg horse under maintenance conditions into consideration. The declarations of the feeds, especially in the case of mineral licks, were frequently not in conformity with the Regulation (EC) Nr. 767/2009 on commercial market introduction and use of feed. Concerning the horses' Se status, only horses receiving Se supplementation either via mineral lick with a Se concentration ≥ 20-50 mg/kg or a mineral or supplementary feed exhibited median serum Se concentrations within the reference range. In 2 of 10 horses with access to mineral licks with molasses containing Se concentrations ≥ 45 mg/kg, serum Se concentration exceeded the reference range at at least at one sampling time point. CONCLUSION AND CLINICAL RELEVANCE: Due to difficulties in their dosaging, the use of mineral licks should be only considered in extensively managed farms with limited access to the individual horse. The recommended Se concentration in mineral licks is recommended to lie in the range of 40-50 mg/kg. In order to attain improved control over Se intake, this trace element ought to be provided by individual feeding using either a mineral supplement or a supplementary feed.