The distribution of whole blood potassium concentration in 1783 Welsh Mountain sheep shows marked bimodality, varying about two modes, of 44 and 14 m-equiv./l.
The difference between high (HK) and low (LK) potassium types was not clear-cut. About 5 % of animals lay in the area where the tails of the two distributions merge.
Haematocrit values and plasma potassium concentrations were used to estimate erythrocyte potassium levels. They confirmed that the bimodality is due to variation within erythrocytes but did not offer a satisfactory method of allocating intermediate animals.