Evaluation of the respiratory elimination kinetics of selenate and Se-methylselenocysteine after oral administration in lambs

Sheep can be acutely poisoned by selenium (Se) accumulating forages which often contain selenate or Se-methylselenocysteine as their predominant forms. Excess Se can be eliminated via respiration. Sheep were given a single oral dose of 0, 1, 2, 3, 4, or 6 mg Se/kg BW as sodium selenate and Se-methylselenocysteine or 6 mg Se/kg BW as sodium selenite or selenomethionine. Expired air samples were collected and analyzed for Se. The Se concentration of the expired air reflected a dose-dependent increase at individual time points for both Se-methylselenocysteine and sodium selenate, however, Se content was greater and eliminated more rapidly from sheep receiving Se-methylselenocysteine. The mean Se concentration in respired air from sheep administered 6 mg Se/kg BW of different selenocompounds was greatest in sheep dosed Se-methylselenocysteine > selenomethionine > sodium selenate > sodium selenite. The Se concentration in respired air of acutely poisoned sheep is significantly different for different chemical forms of Se.