Sheep Copper Deficiency and Swayback Prevention

Copper deficiency in sheep causes swayback (enzootic ataxia) in newborn lambs and a range of production-limiting conditions in adult ewes. Soil-based deficiencies require targeted supplementation balanced against the narrow margin between copper deficiency and toxicity in this species.

Key Facts

Swayback in newborn lambs results from copper deficiency during pregnancy impairing myelination of the developing nervous system
Affected lambs are born with incoordination ranging from mild ataxia to complete inability to stand, depending on severity
Soil copper deficiency is compounded by high molybdenum levels which form thiomolybdate complexes that block copper absorption
Adult copper deficiency causes bleached fleece colour loss, reduced immunity, poor fertility, and delayed oestrus
Sheep are highly susceptible to copper toxicity from oversupplementation — liver copper accumulates silently until a stress event triggers haemolytic crisis and rapid death

Welfare Considerations

Swayback lambs experience motor dysfunction from birth that prevents normal nursing and thermoregulation, leading to rapid hypothermia and starvation if not supported. Mildly affected lambs can survive with intensive nursing but may never achieve full motor recovery. Adult ewes with subclinical deficiency have impaired immunity and reproductive performance without obvious clinical signs. Welfare-centred prevention requires soil and herbage analysis, blood copper assessment in ewes before mating, and targeted supplementation with copper boluses or injection — never blanket supplementation of all animals without blood confirmation given the narrow toxic margin in this species.

What You Can Do

Test soil and herbage copper and molybdenum levels on farms with a history of swayback or production problems before supplementing
Blood sample ewes before mating to determine individual copper status and supplement only confirmed deficient animals
Use long-acting copper oxide boluses for deficient ewes rather than water-soluble supplementation, which is harder to control accurately
Never supplement sheep with copper feeds designed for cattle — the dose is fatal to sheep
Work with your vet and nutritionist to calculate copper supplementation requirements based on blood data and forage analysis, not assumptions about soil type alone