SELECTION FOR PLASMA COPPER CONCENTRATIONS WITHIN HEMOGLOBIN TYPE IN SHEEP

From among 27 rams of hemoglobin type A the 2 rams with the highest plasma Cu concentration and the 2 rams with the lowest were selected on the basis of a single determination. In the same way 4 rams were selected from among the 29 rams of hemoglobin type B. The average difference between the "high" and the "low" rams was 103 .mu.g Cu/100 ml plasma. The rams were mated to 105 unselected females. Lambs born as a result of these matings were blood-sampled on 8 occasions from 3-29 wk of age. The plasma Cu levels of the lambs sired by the "high" Cu rams were higher on average than those sired by "low" Cu rams. The 2 groups diverged from 12 wks of age onward to a maximum difference, at 29 wk, of 18 .mu.g Cu/100 ml plasma. There was also an initial difference of 13 .mu.g at 3 wk but a much smaller one at 6 and 9 wk. There was no corresponding difference in plasma Cu concentration between the offspring of hemoglobin A and hemoglobin B rams. The results are therefore consistent with the hypothesis that the association previously observed in the same flock between hemoglobin type and plasma Cu level is unlikely to be due to an effect of the gene controlling hemoglobin type, but could be due effectively to a linked "Cu gene". Correlations between maternal plasma Cu concentration 3 wk after parturition and lamb''s plasma Cu level showed a marked decline as the lambs grew older, starting from around 0.6 at 3 or 6 wks old. This suggests a maternal environmental influence on lamb''s plasma Cu in addition to any genetic effects.