By Dr Jon Kelly
Trace elements (or macro minerals) are present in soil, grass and feed’s, and although are only required in very small amounts by animals, are essential to the function of many body systems.
The most important trace elements for cattle (of all ages) are Copper, Cobalt and Selenium.
Trace element deficiencies can be caused by rainfall, soil type, pasture species and pasture growth rates. Fertiliser usage can also affect what trace elements are available, for both plants and animals to absorb. A good example of this effect is Molybdenum fertiliser decreases the availability of Copper due to binding with it.
Signs of Trace element deficiency can be broad and non- specific due to the wide variety of body systems affected, but also the degree of deficiency the animal is exposed to, and the class of animal.
General symptoms include:
- Lowered production – milk and meat
- Lowered fertility
- Depressed immune system – more susceptible to disease
- Developmental problems – poor doing or illthrift
It also needs to be recognised that these signs can be seen on a whole mob level, but more commonly as sub set of a whole mob. In other words, a mob run under the same conditions will have some animals that look affected, and others that look “normal”.
Spring 2016 was seen one of the wettest on record (>250mm rain in September and October) in Warrnambool and district. Rapid plant growth, stage of plant growth and significantly more “leaching” of trace elements due to the rain, has seen an increase in clinical trace element deficiency.
The properties and animals we have diagnosed clinical deficiency have all been North of town (in the Hawkesdale- Woolsthorpe – Ballangeich area) and have been a mix of Selenium or Copper deficiency, or both.
Examples of cases we have diagnosed spring 2016 include:
- Dairy Heifers on the point of calving with broken “shoulders”(Copper deficiency)
- Angus Beef calves - poor doing, underweight, scouring and “orange coat”(Copper deficiency)
- Angus beef calves with sudden death, stiff gait, unable to get up – Whit Muscle disease (Selenium deficiency).
Determining the trace element status of your animals can be done by blood testing, liver biopsy and diet assessment.
The end of Spring is the best time for mob based trace element screening. This involves blood testing approximately 6-8 animals and reviewing their diet.
Another tip is that any sudden death through misadventure (e.g broken leg) are a great opportunity to get a liver sample. Pop it in a container, place in the fridge and next time you are in town, drop it into the clinic.
Please speak to one of our vets for more details.