The Turnover Of 75-Selenium - Selenomethionine As An Indicator Of The Status Of Protein Metabolism In Reindeer (Rangifer Tarandus) (Degradation Rate, Reincorporation, Reutilization)

Abstract

The turnover of a single injection of ('75)Se-selenomethionine (('75)SeM), a radio-labeled seleno-analog of the amino acid methionine was used to estimate protein turnover, the irreversible loss of protein nitrogen, in reindeer. ('75)Se-selenomethionine turnover was measured in nine adult female reindeer grazing on natural forage during winter (November-April) and summer (July-August). ('75)Se-selenomethionine turnover was two to four times higher during summer than during the winter months. Seasonal changes in ('75)SeM turnover were believed to be due primarily to seasonal changes in protein and/or methionine intake. The relationship between the intakes of protein and methionine and the turnover of ('75)SeM was determined in ten pen-fed reindeer. Reindeer consumed one of three rations containing 3, 11, or 18 percent crude protein. This resulted in daily crude protein intakes of 1.6, 5.1, or 8.2 g per kg ('0.75) b.w. and daily methionine intakes of 0.01, 0.06, or 0.12 g per kg ('0.75) b.w. ('75)Se-selenomethionine turnover was four times higher for reindeer with high protein and methionine intakes than those reindeer consuming low levels of these nutrients. High positive correlations were found between ('75)SeM turnover and the intake of crude protein and methionine. The method of using ('75)SeM as an indicator of protein turnover showed a good empirical relation, but application to other biological conditions should be accompanied by calibration trials.