This manifested in fawns before weaning where they were arthritic and crippled with a characteristic “bunny-hoping” gait. They died or required euthanasia. Soil fertility was being progressively improved there and the issue became bad around the same time as a sharp spike in soil sulphur (S) and lifting in soil pH, which can make more molybdenum (Mo) available.
A 2016 herbage test showed copper was actually high, but so was S, iron (Fe) and Mo. It’s known that S, Fe and Mo can inhibit copper uptake and it’s likely this was happening here. In the meantime the issue is being dealt with by giving hinds a copper injection and this seems to have resolved the problem for now. Coincidentally, S levels have returned to normal.
Dave Lawrence commented that an injection is more reliable that copper bullets, which don’t always stay where they’re meant to, although bullets tend to provide much longer duration of benefit. He said the copper deficiency was probably a secondary issue caused by the other elements inhibiting uptake.