ROMBACH, E.P.*; BARBOZA, P.S.; BLAKE, J.E.: Trace Mineral Reserves during Gestation in Muskoxen

We studied a captive population of muskoxen (Ovibos moschatus) that experienced reduced growth and development of young (likely caused by copper, Cu, deficiency) to better understand stages of development where trace minerals are critical for survival of young. We examined the role that gestation plays in establishing trace-mineral reserves in fetuses through assessing the distribution of Cu and metalloenzymes (ceruloplasmin and metallothionein) in muskoxen and their fetuses. Hepatic levels of Cu were high in mothers (179 μg.g^-1 whole tissue) and did not change through gestation, whereas fetuses accumulated large reserves (300 μg.g^-1), likely in the form of metallothionein, during the last third of gestation. Furthermore, we hypothesized that Cu supplementation through gestation would increase levels of systemic Cu in the mother, resulting in greater hepatic stores of Cu and metallothionein in the fetus. Nine adult females received weekly injections of Cu-gluconate, and nine received injections without Cu throughout gestation; reserves of Cu in eight newborns were assessed. Activity of ceruloplasmin in pregnant females was used as an index of total Cu in the body. Maternal supplementation had no effect on hepatic reserves of Cu in newborns, likely because the diet was already adequate in Cu, although activity of ceruloplasmin decreased in muskoxen that had not received copper injections, reflecting increased systemic limitations. Gestation, especially the last third, is a critical time for fetuses to accumulate reserves of trace minerals, placing high demands on the mother, which may have important implications for wild populations under conditions of fluctuating forage quality making young susceptible to trace mineral deficiencies.