Published online by Cambridge University Press: 27 March 2009
1. Blood copper data are reported on ninety-four sheep divided into four experimental groups on a “border-pining” hill-side in Northumberland in 1940, in comparison with more extensive findings reported in 1939.
2. The mean value for comparable sheep was 0·080 mg. % in 1940 as compared with 0·086 mg. % in 1939, the overall range, 0·013–0·210 mg.%, being even wider than before.
3. Variations between animals comprising a group were as wide as between groups, and blood levels were not affected by moderate variations in Cu intake. Only in young sheep was there any evidence that a mineralized cake supplement, containing copper sufficient to double the natural grazing intake, had any elevating effect on blood copper.
4. Variations between values for the same individuals in 1939 and in 1940 were as wide as between different individuals in either year. Over 25% of the sheep showed Cu levels in 1940 falling within ±0·01 mg. % of their 1939 values, but nearly 20% showed figures differing by more than ± 0·05 mg. %, irrespective of differences in group treatments.
5. The significance of the figures, for normal. Northumbrian ewes is discussed in relation to those reported for Derbyshire ewes bearing lambs affected with “enzootic ataxia” or “swayback”.