Digestibility and bioavailability of dietary selenium from fishmeal, selenite, selenomethionine and selenocystine in Atlantic salmon (Salmo salar)

Abstract

Four groups of Atlantic salmon (Salmo salar), mean weight 68 g, were given diets for 4 weeks, in which the selenium (Se) was supplied from either fishmeal, sodium selenite, DL-selenomethionine or DL-selenocystine. Selenomethionine was the most digestible (92%) and fishmeal (47%) the least digestible source of Se. This was reflected in plasma Se concentration which was highest in fish given selenomethionine, although the activity of the enzyme glutathione peroxidase (GSH-Px) which contains Se was not significantly increased. Measurement of the GSH-Px:Se ratio indicated that Se supplied as selenite or selenocystine was a better source of Se for plasma GSH-Px than was Se from selenomethionine or fishmeal. Se concentration and GSH-Px activity in liver and erythrocytes were not significantly different in fish given the experimental diets for 4 weeks. © 1989.