Effect of Sulfates in the Diet of Pregnant Ewes on Plasma Concentrations of Copper and Ceruloplasmin in Newborn lambs

The effect of short-term experimentally elevated dietary sulfates on copper status of heavy pregnant ewes and their newborn lambs was studied. Sixteen pregnant Mehraban ewes, 4–4.5 years old, were fed a basal diet containing 0.19% sulfur, 8 PPM copper and 3.9 PPM molybdenum from about the 100th day of pregnancy till 3 days postpartum. During the last 25 days of pregnancy, the animals were fed individually and 10 ewes (the experiment group) received 0.38% extra sulfur as sulfate daily in their diet. Liver copper concentration of ewes was determined at about the 100th day of pregnancy and on the 3rd day postpartum. Plasma concentrations of copper and ceruloplasmin were measured weekly before parturition and also at the 1st hour and on the 3rd day after lambing. Concentrations of copper and ceruloplasmin were also measured in plasma of newborn lambs at the 1st hour (before sucking colostrum) and again on the 3rd day after birth.

In ewes of the control group, liver copper concentration increased significantly (p < 0.05) during the experiment. This increase could be due to removal of animals from pasture and feeding them with a controlled diet. In the experiment group, however, a slight and nonsignificant decrease in liver copper concentration was observed (p > 0.05), which could be due to increased requirements during heavy pregnancy together with the effect of sulfates in reducing the availability of dietary copper. This decline, however, was not sufficient to produce even marginal deficiency. No significant difference was observed in plasma concentrations of copper and ceruloplasmin between the two groups. In newborn lambs, plasma concentrations of both copper and ceruloplasmin were similar at birth. On the 3rd day, however, plasma copper was significantly lower in the lambs of the experiment group (p < 0.05). This may be related to the lower concentration of ceruloplasmin in their blood.

It is concluded that sulfates, in short terms, may not result in copper deficiency in pregnant ewes, but may affect copper metabolism in newborn lambs. Routine experiments conducted on adults to detect copper deficiency seem not to be proper for predicting these changes in newborn lambs.