Utilization of copper during lactation and neonatal development in muskoxen

Abstract

Post-natal availability of copper may affect survival of arctic ruminants such as muskoxen (Ovibos moschatus), because neonates must develop rapidly before their first winter. We hypothesized that supplemental injections of Cu for lactating females would increase Cu in milk and in circulation within their offspring. Milk was low in Cu (<4 μg Cu·g–1dry matter) but was not affected by Cu supplementation through peak lactation. Muskoxen are born with high concentrations of Cu in the liver but low activity of the Cu enzyme ceruloplasmin in serum. Levels of serum ceruloplasmin and Cu increase as neonates mature, reaching adult levels in late summer, but this transition coincides with poor growth and diarrhea. Reserves of Cu established in utero are likely depleted as metabolic processes mature and as young make the transition from a milk-based to a forage-based diet. Therefore, availability of trace minerals in utero and in autumn forages may influence the growth, immune function, and survival of young muskoxen in their first year.