Copper (Cu) metabolism in domestic herbivores as guide to criteria for predicting the Cu nutritional status of wild ruminants in southern Africa

Abstract

In southern Africa game farming has become an effective way of using underutilised resources and a valuable method of preserving and increasing wildlife numbers. However, little is known about the mineral requirements of wild animal species or the assessment of the mineral nutritional status of these species. To establish criteria for estimating the copper (Cu) nutritional status of wildlife, current knowledge about Cu metabolism and criteria for domestic animals has been used. Since the Cu metabolism of ruminants differs substantially from that of non-ruminants, Cu metabolism in domestic species such as cattle and sheep representing wild ruminants, and pigs and horses as non-ruminant species, has been scrutinised to propose criteria for wild bovids in southern Africa. In the adequate range of dietary Cu intakes, literature suggests that hepatic Cu concentrations in ruminants increase linearly with an increase in Cu intake, allowing a relatively reliable measure of sufficiency. In non-ruminants, hepatic Cu concentrations follow a lag phase during which hepatic Cu concentrations remain relatively constant with increasing dietary Cu intakes of more that 25 times their requirements. A consequence is that non-ruminants can tolerate much higher dietary levels of Cu compared to ruminants. It is proposed that at liver Cu concentrations of < 20 mg/kg dry matter (DM), a wild ruminant could benefit from Cu supplementation; liver Cu concentrations of between 20 and 300 mg Cu/kg DM suggest an adequate Cu intake; concentrations of 300 to 500 mg/kg DM indicate a potentially unhealthy accumulation of Cu, while liver Cu concentrations of > 500 mg/kg DM indicate that the animal probably consumed more Cu than required and might be at risk of developing Cu toxicosis.