Variation of the transfer coefficient for radiocaesium transport to sheep's milk during a complete lactation period

Abstract

The variation with time in the transfer coefficient for radiocaesium transport to sheep's milk was measured during an entire lactation period. One hundred and forty ewes, which gave birth around the beginning of November 1990, were used in the experiment. The animals were segregated into group of six ewes and throughout their lactation period, every week one of the groups was given a diet of ground wheat, contaminated with radiocaesium from the Chernobyl accident. Herbage intake, milk yield and radiocaesium concentration in the milk were monitored both during the contamination period and for an additional week while the animals were given a diet of uncontaminated feed. The data were analyzed using a linear compartment model and transfer coefficients were calculated. The results of this analysis showed an increase of radiocaesium activity concentration in the milk by a factor of three, over the 21-week lactation period. However, a significant correlation was found between transfer coefficients for radiocaesium and average daily milk yield, providing evidence for a steady radiocaesium transfer to ewe's milk throughout the loctation period.