Chris Gregory BVSc MRCVS, Molecare Veterinary Services
Diagnosis of mineral deficiencies at animal level can be relatively non-specific, especially if the scenario is complicated or even exacerbated by other problems with similar signs e.g. parasite burdens, pneumonia, poor forage quality.
Trace element (or micro ‘mineral’) deficiencies classically come down to four usual suspects:
- Selenium (Vitamin E)
Deficiencies in one or more of the above elements can be broken down into two categories:
Primary Deficiency – A straight lack of the mineral in the soil/grass/forage.
Secondary Deficiency – The mineral is present at acceptable levels but locked up, or made unavailable to the animal by another antagonist (e.g. sulphur, molybdenum and iron).
Diagnosis of mineral deficiencies will likely involve some combination of clinical observation of stock, soil/forage analysis, blood sampling and eventual response to supplementation.
Some of the classic signs of deficiency are summarised below (Table 1), although whilst they can be useful indicators of a problem, they should not be relied on for specific diagnosis.
Routine soil/forage analyses will flag mineral levels as standard parameters, and will also give an estimation of how available the mineral is relative to other antagonists. This type of analysis is a good first port of call but may or may not correlate with clinical signs in stock.
Blood sampling can be useful in certain cases to confirm a suspected deficiency at any one point in time. However, it will not take into account dietary variations over time or natural daily fluctuations.
Once a deficiency is highlighted, supplementation trial is most likely the next step. There are many methods of supplementing the animal, e.g., mineralised blends/concentrated feed, oral drenches, slow release oral boluses, external treatments and injectable preparations. All have their benefits and drawbacks and should be tailored to fit in with farm management practices and requirements.
Care should be exercised as dose rates are nominally based on predicted daily requirements. Over-supplementation is uncommon but does occur, mainly with respect to multiple copper sources. Response to supplementation should be monitored closely, e.g., growth rates and clinical improvement.
|Copper||Most commonly occurs as a secondary deficiency on pastures high in antagonists, e.g., Molybdenum (‘teart pastures’), sulphur and iron
||Poor growth rates in young stock at grazingDiscolouration of the skin around the eyes ‘spectacled appearance’
Thin poor quality coat
(NB. High levels of Molybdenum can cause scours and chronic anaemia)
|Selenium (Vitamin E)||Deficiency more common in home grown cereals/root crops||Still-born/weak new-bornsAt first turn-out: sudden death, muscle stiffness, struggle to breath
Poor immune responses
|Cobalt||Almost exclusively a primary deficiency in regions where soil is low in cobalt||Reduced intakes/feed conversion efficiencyChronic anaemia
Thin skin and poor hair coat
|Iodine||Primary deficiency in low iodine soilsLow selenium can cause secondary iodine deficiency||Goitre’s (swelling on the neck) in new-bornsWeak or still-born +/- patchy hair loss and puffy skin
Table 1: Common clinical signs of trace element deficiencies