Copper levels have to be low for several months before deficiency signs are noted, so the aim is to maintain reserves at adequate levels at all times to prevent production / reproduction losses. Reserves tend to be lowest in autumn and late spring i.e. at mating!!!
The only way to measure reserves in the live cow is by liver biopsy (35% or more of BLOOD copper results will be WRONG in terms of actual copper reserve determination!!!)
NB While we consider PKE to almost be a Copper supplement, we have had a couple of herds in the autumn test very LOW for copper despite substantial PKE inputs. If feeding PKE it is still very important to check copper levels not only to ensure they are not too high, but also to ensure they actually ARE adequate.
If supplementation is required it needs to be given more than 4 weeks before mating start, so biopsies need to be done early September at the latest.
Liver Biopsy
This is a much better alternative to blood sampling when no culls are going to the works. The liver is the store for Cu, Selenium (Se) and Cobalt and thus more accurate to use for evaluation than blood. Only 4-6 animals are needed for liver biopsy. Animals need to be properly vaccinated for Blackleg.
Biopsy, under local anaesthetic is best done on cattle immediately off pasture so that the full rumen holds the liver firmly against the diaphragm. The animals need to be restrained in a head bail and crush with access to its right side, or lined up in a herringbone shed.
