Of
all of the minerals, iron seems to be the one at the forefront of many owners
mind; perhaps because we have become accustomed to associating a feeling of
tiredness and not eating enough green vegetables with iron deficiency and
anaemia. However, when it comes to our horses, should iron be a primary concern
and is an additional supplement necessary?
Iron
is a ‘micro mineral’ or ‘trace element,’ meaning that it is required in smaller
amounts by the horse. Its primary function lies in oxygen transport and
consequently, approximately 60% of the iron in the horse’s body is in
haemoglobin – the protein which carries oxygen and gives blood its red colour.
Despite
the fact that iron does not provide any energy, iron rich supplements are often
propositioned as aid to improving energy levels, enhancing performance and as a
‘tonic’ or ‘pick–me-up’ for horses in hard work or recovering from illness. In
truth, there is no scientific rationale to support this and iron is a great
example of the fact that more does not always equal better. Mature horses need approximately 400-600mg of
iron per day, equal to only 0.4-0.6g. Iron deficiency in horses is rare even in
hard working horses and tends only to occur as the result of significant blood
loss (including internal blood loss). In fact, toxcosis is far more common than
deficiency in horses.
The
National Research Council (NRC-accepted institute for standardising animal
diets) sets the maximum tolerable level for iron at 500mg/ kg of feed, although
some nutritionists feel that due to the potentially high levels is some
forages, this can be increased to 800mg/ kg (equal to 8-9.6g per day in a 500kg
horse). Toxicosis may cause depression, dehydration, diarrhoea, an increased
risk of bacterial infections, liver failure and in extreme cases death;
particularly as result of over supplementation in foals where absorption is
more efficient.
For
the most part, iron supplements are unnecessary and should only be considered
following a confirmed clinical deficiency. Although the addition of an iron
based supplement will not automatically result in toxicosis, they have the
potential to do more harm than good; particularly as many owners do not have
their forage analysed. If poor performance is a concern and the potential for
underlying medical conditions can be ruled out, consider factors such as
fitness, condition, hydration, temperament and feeding a balanced diet rather
than reaching for an iron supplement.
