The accretion of copper and of zinc by the foetuses of prolific ewes

Abstract

1. The amounts of copper and zinc in the foetuses of ewes carrying from one to four lambs were measured at different stages of gestation and estimates were made of the amounts of these metals in their livers.2. The accretion of Cu and Zn could be described by growth equations of the Gompertz form, from which could be derived estimates of the instantaneous and fractional rates of deposition of these metals in the foetal body.3. Between the 80th and 144th day of gestation the instantaneous rates of deposition of the metals increased exponentially, and at the end of pregnancy were calculated to be 0.24 and 2.0 mg Cu and Zn/d respectively in the triplet lamb foetus. The corresponding total accretions were estimated to be 10 and 69 mg respectively.4. The fractional rates of live-weight gain and of deposition of Cu were similar and decreased at similar rates; that of Zn deposition decreased much more slowly.5. The proportion of whole-body Cu estimated to be in the liver was always greater than 50 %. The amount of Zn in the liver remained constant and contributed 72 % of the total body Zn at 80 d but only 8 % at 144d.6. The relative amounts of Cu and of Zn accrued per unit body-weight gain were not constant during the development of the foetus. As foetal numbers increased the amounts of each metal deposited in the foetus decreased more rapidly than did foetal weight.7. The results are discussed in relation to the demands for Cu and Zn during pregnancy in sheep.

Relationships between Maternal and Fetal Liver Copper, Iron, Manganese, and Zinc Concentrations and Fetal Development in California Holstein Dairy Cows

“…5,51-53 A decline in fetal liver Zn concentration with age also has been described for sheep. 19,54,55 Although a negative interaction of Zn and Cu has been suggested to occur, fetal Zn and Cu were positively correlated in this and in the Canadian study. 14,15,24,25,34,43 O ur observed positive correlations between fetal size and fetal Zn and between fetal Zn and fetal Cu can be attributed to induction of fetal metallothionein.…”

“…An increase in fetal Cu with fetal size has previously been reported for cattle and sheep. 14,15,54,55 In humans, fetal Cu concentrations reportedly increased or remained stable through gestation. 5,51,53 Bovine maternal and fetal Cu were positively correlated in this and previous reports.…”

The potential for improving physiological, behavioural and immunological responses in the neonatal lamb by trace element and vitamin supplementation of the ewe

“…However, lambs can also be born with liver Cu stores that can sustain the animal for long periods in the face of inadequate intake. Williams et al (1978) have calculated that liver Cu could maintain the lamb for 2 weeks in the absence of dietary Cu. Further, since the absorption coefficient for Cu by the neonate approaches 1 and milk Cu is greatest in early lactation (Wiener et al, 1984), Cu deficiency is unlikely if the ewe is Cu adequate.…”

Effect of Gestation and Maternal Copper on the Fetal Fluids and Tissues Copper Concentrations in Sheep

“…Fetal liver Cu increased as fetal age increased and was less than to maternal Cu in early gestation and there was no differences between maternal and fetal liver Cu in late gestation, while fetal liver Cu was significantly higher than that of the maternal liver through gestation (Gonneratne and Christensen, 1989a), as well as Cu concentration was significantly increased in early gestation than that of late gestation in the fetal liver (Abdelrahman and Kincaid, 1993) and kidney while (Richards, 1999) found that in fetal kidney, Cu concentration did not change significantly with gestation. An increase in fetal Cu with fetal size has previously been reported for cattle and sheep (Gonneratne and Christensen, 1989a;Williams et al, 1978;Williams and Bremn, 1976). Numerous studies have shown significant correlations between fetal and maternal tissue copper concentration.…”