AQHA January / February Magazine AQHA JAN-FEB 2020 PRINT | Page 21

WHAT DO WEANLINGS NEED...
The term ‘Developmental Orthopaedic Disease’ (DOD)
was coined at a symposium sponsored by the American
Quarter Horse Association in 1986. It was used to
describe any orthopaedic problem that involved
tendon, joint or bone in growing horses. The diseases
encompassed by this definition are osteochondrosis
(OC), osteochondrosis dessicans (OCD), physitis and
epiphysitis, angular limb deformities (ALD), flexural
deformities (including contracted tendons) and
wobblers (cervical vertebral malformation). Despite
considerable research, there’s no single cause for any
of these.
Creep feeding became the norm after research in
the 1960’s into mares milk found that around 3
months after birth, the milk could no longer meet the
requirements of the growing foal. High energy grain
and supplements were often provided free-choice to
mares and foals – and the first reports of unusual foal
lameness began to appear in the veterinary literature.
Excess protein was blamed and this is still quoted today
even though the theory has since been unequivocally
and consistently discredited. Recent and ongoing
studies into the high incidence of DOD have found the
following risk factors: rapid growth from over-feeding;
trauma to joint cartilage due to excess body weight;
intermittent or irregular exercise; mineral imbalances;
failure to accurately include sugar and starch from
high-energy pastures; high sugar-starch (called NSC or
non-structural carbohydrate) feeds.
Maximum growth is not compatible with optimum
skeletal development. Optimum growth is the goal so
a broad understanding of how and when weanlings
and yearlings grow can help guide decisions on what
and how to feed. Bone and muscle have their own
windows of growth. The 3 most rapid growth periods
for bone are: from 4 months before, until one month
after birth; between 6-12 months of age, and just
after puberty. The period of muscle growth - when the
cells increase in size and number to achieve genetic
potential – is between 2 and 24 months of age. Height
is an indicator of bone growth whereas body weight
and condition reflect muscle and fat deposition.
If nutrition is unbalanced or incorrect during these
periods, the opportunity to achieve optimum muscle
and bone development – and minimise the risk of
future unsoundness – will be missed. The period
of maximum risk for the development of skeletal
abnormalities occurs when height and weight gain are
JANUARY/FEBRUARY ISSUE 2020
PG.19