Developmental Orthopaedic Diseasein young Thoroughbreds can be directly linked to racing performance later in life. Researchers have found that the type and location of juvenile lesions can affect when those horses race, how well they race, how long they’ll race, and if they’ll even end up racing at all.
However, the way that we feed broodmares and young horses can help them to develop strong, properly formed bones and joints, increasing their chance of making it to the racetrack.
Developmental OrthopaedicDisease (DOD) is a term coined in 1986 to describe all musculoskeletal problems in growing horses. These growth disturbances include physitis, osteochondritis dissecans, subchondral bone cysts, and flexural limb deformities.
Research has shown that DOD cannot be blamed on a single cause. Factors that can lead to DOD include genetic predisposition,trauma, stress on bones due to inappropriate exercise or obesity, rapid growth, and inappropriate or imbalanced nutrition. Combinations of these factors might lead to DOD. Environmental or management factors could provide triggers. Developmental orthopaedic disease can occur anytime between birth and 1½ years of age but most significantly appropriate nutrition of the broodmare lays the foundation for proper bone development, thus sidestepping developmental problems and possible unsoundness.
The nutritional requirements of a broodmare can be divided into three stages.
Early pregnancy.The foetus is small during the first five months of pregnancy. Even at seven months of pregnancy, the foetus is only about 20% of its weight at birth. Because this equals less than 2% of the mare’s weight, the foetus’s nutrient requirements are minuscule compared with the mare’s own maintenance requirements. Therefore, the mare can be fed essentially the same as if she were not pregnant.
Late pregnancy. The foetus begins to develop rapidly after seven months of pregnancy, and its nutrient requirements become significantly greater than the mare’s maintenance requirements.
Digestible energy requirements only increase about 15% over early pregnancy, however, protein and mineral requirements increase to significantly.
Trace mineral supplementation is critical during this period because the foetus stores iron, zinc, copper, and manganese in its liver for use after it is born. The foetus has developed this nutritional strategy of storing trace minerals during pregnancy because mare’s milk is quite low in these elements.
New Zealand researchers studied the effect of copper supplementation on the incidence of developmental orthopaedic disease in Thoroughbred foals.
Pregnant Thoroughbred mares were divided into either copper-supplemented or control groups.
Live foals born to each group of mares were divided into copper-supplemented or control groups.
Copper supplementation of mares was associated with a significant reduction in the occurrence of physitis (inflammation of the bone growth plates) of foals at 150 days of age.
Foals from mares that received no supplementation had significantly more incidence of physitis than foals out of supplemented mares.
A significantly lower incidence of articular cartilage lesions occurred in foals from supplemented mares.
However, copper supplementation of the foals had no significant effect on the severity of developmental orthopaedic disease.
Mares in late pregnancy are often overfed energy in an attempt to supply adequate protein and minerals to the developing foal. If the pregnant mare becomes fat during late gestation, she should be switched to a feed that is more concentrated in protein and minerals so that less can be fed per day. Stud balancers are ideal in these situations.
Lactation. A mare’s nutrient requirements increase significantly after foaling.
Mares in early lactation usually require from 5-7Kg of concentrate feed per day depending on the type and quality of forage they are consuming.
This should be fortified with additional nutrients to meet the lactating mare’s needs. Trace mineral fortification is not extremely important for lactating mares because milk contains low levels of these nutrients and research has shown that adding more to the lactating mare’s diet does not increase the trace mineral content of the milk. Calcium and phosphorus are the minerals that should be of primary concern during lactation.
If the broodmare has been fed properly during late pregnancy, it is unnecessary to supplement the suckling with minerals until it reaches 90 days of age. At this time, moderate amounts of a specifically formulated foal feed, which can be introduced and gradually increased until the suckling is consuming around0.5 kg per month of age.
The most critical stage of growth for preventing developmental orthopaedic disease is from weaning to 12 months of age, when the skeleton is most vulnerable to disease and nutrient intake and balance is most important. Weanlings should be grown at a moderate rate with adequate mineral supplementation and during this phase many will thrive with access to good quality pasture, hay, balanced with a fortified, low energy, protein, vitamin and mineral balancer pellet.
Once a horse reaches 12 months of age, it is much less likely than a younger horse to be affected by developmental disease. Many of the lesions that become clinically relevant after this age are typically formed at a younger age.
However, optimum and balanced nutrition remains important for the yearling. Delaying the increased energy intakes that are required for sales prepping as long as possible is wise as the skeleton is less vulnerable to developmental orthopaedic disease as the yearling ages.
Increasing energy intake 90 days before a sale is enough time to add the extra body condition that is often expected in a sales yearling.
Proper nutrition of the mare throughout pregnancy and lactation and of the young horse during its first two years of life will help prevent developmental orthopaedic problems and increase the chances of a young racehorse making it to the track for its first race of many.