Alternative selenium supplement for sheep

Abstract

This study investigated Se-dependent parameters in ewes after supplementation with an experimental Se product (P-Se) in comparison to sodium selenite. Six Dorset ewes averaging 93.0 (SE = 2.5) kg initial body weight were used in a replicated 3 × 3 Latin square design experiment balanced for residual effects. The study began with a 2-wk background, low-Se period and had 3 experimental periods of 3 weeks each, with 2-wk washout periods between them. The treatments studied were: (1) unsupplemented control (basal diet containing 0.065 mg Se/kg dry matter, DM); (2) basal diet supplemented with Na-selenite providing 0.25 mg Se/kg DM; and (3) basal diet supplemented with P-Se (containing 29 % Na-selenite and 71 % amorphous elemental Se) providing 0.27 mg Se/kg DM (P-Se). Blood samples (taken from the jugular vein) and spot urine and fecal samples were collected the day before the start of each experimental period, on the last day of each washout period, and once weekly during the experimental periods for analysis of Se concentration and glutathione peroxidase (GPx) activity (blood plasma only). Ewes supplemented with P-Se and Na-selenite had increased (P < 0.001) plasma Se concentration compared with ewes fed the control diet. Absolute concentration of Se in plasma was greater (P < 0.001) for ewes fed Na-selenite (80.9 μg/L) than for ewes fed P-Se (72.3 μg/L). Absolute plasma GPx activity was greater (P < 0.001) for ewes fed Na-selenite and P-Se compared with the control, but was not different between the Se treatments. Concentration of Se in fecal matter was greater (P < 0.001) for both Se sources than the control and fecal Se concentration was higher (P < 0.001) for P-Se compared with Na-selenite. Absolute Se concentration in urine was greater (P ≤ 0.003) for Na-selenite than the control and P-Se. Selenium supplementation of ewe diet increased Se concentration and GPx activity in blood plasma, regardless of Se source. Although P-Se had slightly inferior absorption, compared with Na-selenite, our data indicate that it can potentially be an effective source of dietary Se for mature ewes, but further studies are needed to confirm these results in other farm animal species and physiological stages.