There are many complex interactions and influencing factors affecting both the uptake and utilisation of trace elements at the soil, plant and animal level. All these factors, plus the farm's history and fertiliser use, should be considered before administering trace elements. Treatment without being aware of the farm's mineral status is wasteful, potentially harmful, or even fatal to livestock.
The diagnosis of trace element status is accurate and inexpensive. Both blood and liver sampling can be used in conjunction with soil and/or plant analyses to develop a trace element supplementation programme.
It is best to obtain livers from cattle for the analysis of copper status in the autumn. This allows predictions as to whether supplementation is required prior to winter and spring when the availability of copper from the soil and pasture decreases. The animals' requirements for copper are highest at this time of the year, particularly in young or heavily pregnant animals. Blood samples are only useful for the diagnosis of copper deficiency.
A good relationship exists between the level of selenium in the soil, plant and animal. If the selenium in the soil is known to be low, then the likelihood of having selenium deficiency in your livestock will be high. In saying this, soil and plant analysis will not tell us the amount of selenium being absorbed. Therefore liver sampling or bloods are better predictors of the need for supplementation. Samples can be taken from cattle and sheep at the same time as for copper, in the autumn.
In the Manawatu, severe cobalt deficiency in lambs is rare. This is because most areas are adequate, or only marginal in cobalt. A response to vitamin B12 supplementation is unlikely unless there has been severe erosion (weathering), leaching, repetitive cropping or fertiliser use. Clinical signs of cobalt deficiency are anorexia and poor growth rates in lambs.
If you are not seeing this in your lambs, you are very unlikely to see cobalt deficiency in adult sheep or cattle on the property. It is best to test lambs at weaning in December, a time when liver reserves of vitamin B12 will be lowest. Liver selenium and copper could be tested at the same time but because sheep have lower requirements for copper (unless they are Finns!), this may not be necessary depending on the farm's history.
Liver samples can be taken from the live animal, or at the time of slaughter.
If you wish to have samples collected at the works, or would like to have liver biopsies taken, please contact us at Totally Vets to make the necessary arrangements. Together we can then make informative decisions regarding the treatment options available.
