Trace elements are natural minerals required in very small amounts by the body for various metabolic processes. Typically they are not stored well in the body, so need to be constantly ingested in tiny amounts. If the body is deficient, the metabolic processes will be adversely affected.
Copper is the main trace element where deficiency is likely to be an issue in deer. Cobalt, iodine and selenium deficiencies also occur but are much less common.
Generic causes of trace element deficiencies
Deer get trace elements from their food sources. If soil trace element levels are low, they will also be low in the pastures and forages on which the deer feed.
In addition, the absorption by deer of nutrients (including trace elements) is affected by the balance of nutrients in the feed, so deer can become deficient in trace elements as feed sources change.
|Element||Specific cause of deficiency||Clinical Symptoms||Sub-clinical symptoms|
The copper storage capacity of deer (in the liver) naturally declines during winter and early spring.
Increasing molybdemum and sulphur intake can reduce copper absorption and storage in the liver.
Low cobalt pumice soils, usually of the North Island.
Reduced production of vitamin B12 and consequent disruption to gucose production.
|Selenium||Selenium maintains the integrity of cells and destroys free radicals which can harm cells.||
|Iodine||Grazing of hinds on low iodine feed such as clover and brassica during mid to late gestation||
The best time to check copper status is March to April, when levels are naturally at their highest. If levels are only just adequate it is worthwhile testing again during July to September, to ensure levels have not dropped further. Taking a liver biopsy or serum samples from several deer is one option. Another option is to get liver samples taken from a line of deer being sent for slaughter. This is known as an Optigrow Test. Talk to a veterinarian or processing plant agent to organise this.
Deficiency is defined as when liver tissue copper concentrations (µmol /kg) are less than 60 or serum levels are less than 5 µmol /litre. Deer are at risk of disease or impaired growth rates at this level.
Table A: Copper levels in the liver and serum considered to be deficient, marginal or adequate for deer.
|Liver (µmol/kg fresh tissue)||<60||60-100||>100|
|Serum (µmol /litre)||<5||5-8||>8|
Cobalt levels can be assessed by liver biopsy or Optigrow test.
Selenium levels can be checked by a blood or liver sample, or Optigrow test. It is important to know when the herd was last supplemented (if at all).
There is insufficient data on deer to be sure of the production and health responses following different levels of supplementation of all four trace elements.
Growth responses from copper supplementation have only been reported in two of eleven trials. Most importantly, the responses were seen when deer had serum levels below 5 µmol/kg (considered to be quite low). There is no published data on the impact of copper supplementation on the reproductive performance of deer. In one study liver concentrations were lower in wapiti and wapiti/red hybrid deer than in red deer on the same pastures, suggesting they were more susceptible to copper deficiency.
No responses to vitamin B12 supplementation in deer have been demonstrated in research but supplementation is a common practice. Research suggests young red deer hinds appear to be less susceptible to cobalt deficiency than lambs.
Two selenium response studies showed no difference in growth rates between treated/untreated deer. Selenium deficient fawns can have lower growth rates.
No animal production response to iodine supplementation in deer has been reported.
Developing an animal health plan to prevent deficiencies can be done in consultation with a veterinarian. There are several approaches and more than one may be needed.
Copper injections, copper-oxide needles (via a bolus), salt blocks with added copper, or the application of copper to pasture can all lift copper levels. Topdressing copper at 12kg copper sulphate/hectare in March lifted pasture concentrations to 45mg Cu/kg dry matter and maintained adequate copper levels in weaners for ten months. Copper can be added to silage when it is being made.
Cobalt deficiency (B12 deficiency) can be prevented by B12 injections. Cobalt fertiliser can be applied to pasture.
Injectable selenium will lift and maintain blood selenium concentrations for at least a year. Putting prills on pasture or a selenised anthelmintic drench are two more options for preventing deficiency. Selenium deficiency can be corrected by using fertilisers containing selenium at the rate of 1 kilogram per hectare. Selenium in high doses can be toxic so do not combine treatments e.g. oral plus injection.
Oral potassium iodine, given to hinds in the last half of pregnancy, was effective in preventing goitre in fawns. An intramuscular injection of iodised oil will give six months of adequate iodine levels. Brassica crops are low in iodine so supplementation may be required during extended grazing of this crop.
Deer grazing chicory in autumn had higher mean liver copper concentrations, than deer fed ryegrass/white clover pasture (333 versus 160 µmol /kg). This is because the chicory had more copper in it.
Information on Copper is available in a convenient DINZ Deer Fact sheet (October 2016). Download your own copy here >>