Copper Requirements of Pregnant Ewes under Conditions of the Arid Zone in Russia

The copper requirements of pregnant ewes in the environment of the arid zone in the Republic of Kalmykia have been studied. The organ and tissue analyses have shown that the copper quantitative concentrations in the fetal tissues and organs tend to vary depending on its age. The maximum copper contents are recorded in the bone tissue and the skin (1839.7 and 1714.08 μg%, respectively) of the fetuses of 100 days of age and in the bone tissue and the liver (1843.08 and 1261.04 μg%, respectively) of the 145-day-old fetuses. In the bone tissue, the percentage of the element was relatively steady during the period of the prenatal development and varied in the range of 1839.7–1843.08 μg%. The blood copper level has slightly increased for the survey period; the blood mass increased 5.84-fold. The total amount of copper in the blood of the fetus at the age of 100 days was 111.21 μg%, while it increased up to 717.33 μg% in the blood of the 145-day-old fetus. For the period of the fetal development, the copper contents in the muscle tissue and the sheepskin with wool decreased from 957.06 to 52.53 μg% and 1714.08 to 170.7 μg%, respectively, while the total amount of this element in these tissues decreased from 3531.07 to 1020.5 μg and from 1458.65 to 1309.05 μg, respectively. The liver copper content elevated with the gestational age by 37.14 μg%, it comprised 1261.04 μg% up to the age of 145 days, and the total content increased 3.1 times. The relative percentage and the total content of copper in the lungs increased by 77.29 μg% and 4.3 times, respectively, between 100 and 145 days of age generally due to the increase in the organ masses. The total copper content in the 100-day-old and 145-day-old fetuses comprised 6.95 and 9.74 mg, respectively. The copper doses at the stages of early (55 days), middle (100 days), and late (145 days) gestation of the Kalmyk fat-rumped meat sheep were determined to be 12.93, 14.02, and 15.34 mg, respectively. Taking into consideration the fact that the dietary copper absorbtion rate is in the range of 71.05–73%, the fat-rumped ewes entering early, middle, and late pregnancy should intake 18.2, 19.3, and 21 mg dietary copper, respectively. The dietary copper intake norms per 1 kg dry matter intake are 11.0, 7.9, and 8.0 mg; the copper intake norms per 1 kg live weight should be 0.30, 0.32, and 0.35 mg.