Tibial dyschondroplasia (TD)

Occurrence: About 1% of all heavy meat type birds reared around the world have some degrees of this disease.
Species affected: Broilers and turkeys
Age affected: 5 to 8 week old
Causes: This disease is not contagious. Genetic and/or dietary (cation ‑ anion ratio) of the ration or high phosphorus relative to calcium) factors may be involved. Grain high in Fusarium roseum or fungicide (tetra methylthiuram sulfate) can cause the disease.
Effects: Lameness in as many of 30% of the flock (reluctance to move, a stilted gait, and
bilateral swelling of the femoral‑tibial joints) can be seen. Leeds to trimming and downgrading in processing plant.

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Mode of transmission

Noncontagious. Physiological disturbance.

Clinical signs

Bowing of the bones is evident and is more severe in roaster birds or males kept over 8 weeks for de-boning with body weight over 5 lbs or 2.2 kilograms.

Postmortem lesions

Proximal tibiotarsal bone is enlarged and contains an abnormal mass of cartilage (failure of cartilage in growth plate to become calcified). Fractures below the abnormal cartilage may occur.

Tibial dyschondroplasia (TD)

Diagnosis

History, clinical signs and postmortem lesions (abnormal mass of cartilage in tibial head) are characteristic. Microscopically, dyschondroplasia is characterized by persistence and accumulation of pre-hypertrophic cartilage and begins as early as the first week of age. Chondrocytes in abnormal cartilage are smaller and shrunken. It simulates perosis, rickets, and osteochondrosis (necrosis of growth plate primarily in the vertebrae and femoral head). Lithoscope can detect TD in birds as young as 1 week of age. This machine is used by basic breeder companies to select out TD in their genetic lines.

Prevention

Slow the growth rate by using lighting or feed restriction program and select strains with a lower incidence of TD.

Treatment

Diet changes will reduce the disease such as reducing phosphorus relative to the level of calcium. Feed a diet free of Fusarium and tetramethylthiurams sulfate.

Tibial dyschondroplasia insights

Securing carcass 
quality with minerals

Over the last 5 years broiler carcass 
prices remained below 1.8 euro/kg and cut prices were stagnating ranging from 1 to 2.5 Euro/kg of carcass. Good carcass quality has become a minimum 
requirement for trading and a constant focus on preventing downgrading is imperative. Trace element 
supplementation in feed can help.