Today, a few differing sources of selenium (Se), i.e. inorganic, organic, and nano forms of Se, are used as feed supplements for poultry. Published research indicates that nano-Se and organic Se possess comparable efficiency to inorganic Se in increasing GSH-Px activity of plasma and various tissues, but they deposit at higher rates in various tissues. However, there are principal differences in absorption mechanisms, metabolism, and efficiency of these three forms of Se. The aim of this review was to analyze the available literature on the effects of different Se sources and levels in the diet on glutathione peroxidase (GSH-Px) activity, tissue Se distribution and growth performance in poultry. Higher levels of Se increase GSH-Px activity in the body, but this reaches a plateau even if Se concentrations in diet increase further, while the deposition of Se in tissues increases as Se content in diet increases. In addition, many studies have shown the positive effects of adding Se to diet on growth performance in poultry. Optimal Se supplementation is necessary not only for good poultry health but also to ensure and preserve meat quality during storage and to provide human beings with this microelement.

The present study was conducted to assess effects of selenium (Se)-yeast supplementation on glutathione peroxidase activity, Se levels in tissues, gr

The physicochemical parameters (free acidity, moisture content, sucrose content, hydroxymethylfurfural, reducing sugars, electrical conductivity, diastase activity and water-insoluble content), elements (Cu, Fe, Zn, Mn, Cr, Co, Ni, Se, K, Na, Ca, Mg) and heavy metal/metalloid concentrations (Cd, Hg, Pb and As) of 84 honeys (linden, multifloral, honeydew and acacia) from Serbia, were analyzed using ICP-MS. Concerning the physicochemical parameters, all tested honeys were found to meet European Legislation (EC Directive 2001/110). Potassium was the major element, ranging between 943.9 ± 538.6 mg/kg and 2563 ± 1817 mg/kg. Statistical analysis showed significant differences in the concentrations of Zn, Mn, Co and Na between the honeys. Selenium and Hg levels were below the limits of detection. Positive correlations were found between electrical conductivity and most of the elements. The present study showed that Serbian honey examined were of good quality according to its physicochemical parameters and met safety criteria concerning the concentrations of Cd, Hg, Pb and As.