The transfer of radiocaesium to ewes through a breeding cycle – an illustration of the pitfalls of the transfer coefficient

Review of Russian language studies on radionuclide behaviour in agricultural animals: 3. Transfer to muscle

“…It was concluded from both experiments that there were no statistically significant differences in F f values measured for sow muscle at different stages of pregnancy except in the earliest stage when mean transfer coefficients were 15-20% lower than those measured later (p < 0.05). This conclusion is broadly consistent with data from studies with pregnant sheep by Beresford et al (2007a) who suggested that this was because the dry matter intake of pregnant animals was not substantially different to that of barren animals (see comment above on age effect).…”

Generic approaches to transfer

“…Conversely, the radionuclide tissue concentration predicted for any organism consuming the same radionuclide concentration in a food source would be relatively independent of the organism's body weight. This exact behavior has been observed for wild species (Beresford, 2003) and sheep (Beresford et al, 2007). The allometric equations and parameters previously discussed were also used to estimate transfer factors as a function of size of the animal:…”

The transfer of radionuclides from saltmarsh vegetation to sheep tissues and milk

“…It is therefore possible that radiocaesium transfer coefficients to the tissues of the study animals were higher than would have been the case if dietary requirements had been met. As this is likely to be a consequence of the inclusion of dry matter intake within the estimation of the transfer coefficient (see discussions by Beresford et al, 2007;Ng et al, 1982) it is probable that other transfer coefficients reported here may also be higher than if the animals' intake had met their requirements. Note this will not impact on estimated concentration ratios (as these do not include dry matter intake within their derivation) unless absorption from the gastrointestinal tract was influenced (see discussion above).…”

“…In part, some of the differences in transfers of radionuclides to ewes and lambs may be as a consequence of a greater rate of uptake (shorter biological half-life) of lambs compared to ewes since this would lead to activity concentrations in lambs being closer to equilibrium than those in ewes. It is also likely to be a consequence of the method of calculating transfer coefficients as this utilises dietary dry matter intakes which were higher for ewes than lambs (see discussion in Beresford et al, 2007); this is likely to be the reason for less significant differences being observed between ewes and lambs when transfer was expressed as the concentration ratio. However, as most previous works report transfer coefficients we have to compare our results to these in the following discussion.…”