Influence of husbandry on the transfer of radiocaesium from feed to milk during the winter that followed the Chernobyl reactor accident.

The release of activity from the Chernobyl nuclear reactor resulted in deposition of radionuclides throughout the UK in early May 1986. Since that time, the transfer of radiocaesium from feed to milk has been followed at two farms that differ in both location and husbandry practice. This paper concerns the winter of 1986/87, when activity concentrations in milk increased because of the consumption of silage prepared earlier in the year. Silage-to-milk transfer coefficients have been estimated which suggest that, when incorporated into prepared silage, radiocaesium from Chernobyl is less available for transfer to cows' milk than soluble caesium-134 applied directly onto pasture. The measured activity concentrations in milk have been compared with those predicted by the NRPB model FARMLAND; despite differences between the husbandry practice assumed in the model and those observed in practice, the model provides an adequate radiological assessment of the feed-cow-milk pathway after an accidental release of radioactivity.