Dry matter intake - a generic approach to predict the transfer of radiocaesium to ruminants?

¹ Centre for Ecology & Hydrology, CEH Merlewood, Windermere Rd., Grange-over-Sands, Cumbria LA11 6JU, U.K.
² Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH, U.K.

Abstract

We have previously demonstrated a relationship between dry matter (DM) intake and the degree of transfer of radiocaesium to the muscle of adult sheep. Here, we present the results of an experiment during which we examined the effect of lamb growth and protein turnover rates, brought about by controlling feed DM intakes, on radiocaesium transfer and turnover. Lambs with high DM intakes and, as a consequence, high rates of growth, had a lower mean radiocaesium transfer coefficient from the diet to muscle than lambs with lower intake and growth rates. Furthermore, high rates of dry matter intake decreased the biological half-life of radiocaesium from muscle. The administration of [³⁵S]-methionine to the study lambs enables us to suggest that radiocaesium transfer may be related to protein turnover. When the results were compared with those of other studies using sheep, a consistent relationship between DM intake and radiocaesium transfer across all animals regardless of age or physiological status was observed. Extrapolation of the relationship to DM intake rates appropriate to cattle predict radiocaesium transfer coefficients in broad agreement with reported values.