Deep pectoral myopathy (green muscle disease)
Species affected: Fast growing broilers and turkeys.
Causes: Hereditary predisposition
Effects: Metabolic disease resulting in swelling in a tight fascia (band) of the underlying breast muscle. Streaks of white to greenish band of muscles causing the breast muscles to become enlarged. Either side of the breast muscle can become enlarge. Leads to trimming and downgrading in the processing plant.
Ischemia (inadequate circulation of blood) causes the swelling in a tight fascia (band) of vigorously exercised muscle. There is some evidence of hereditary predisposition, rapid growth rate, and increased handling in turkey breeder hens during artificial insemination.
Mode of transmission
The cause is a lack of oxygen due to improper blood supply or necrosis around tissues or blood vessels. It is non‑contagious and no specific nutritional factors may influence the condition.
This is a processing plant problem. No problem is noted in the field.
Unilateral or bilateral lesions, which do not affect the health of the bird, may occur followed by more chronic lesions resulting in dimpling or flattening of the breast muscle which can be palpated. The whole deep pectoral muscle is swollen, pale and edematous with necrosis in the middle 1/3-3/5 of the muscle, which is only evident after processing or necropsy. In other lesions, the edema disappears and the necrotic muscle becomes more prominent and drier with greenish areas. Necrotic muscle shrinks and may be enclosed in a fibrous capsule. The sternum adjacent to the necrotic muscle becomes roughened and irregular.
Gross (greenish muscles) and microscopic lesions are characteristic. Microscopically the fibers are swollen and eosinophilic with discoid necrosis. Nuclei are absent or faint. Surrounding the necrotic tissue are inflammatory reactions. Vascular lesions consist of thromboses, intimae proliferation, and aneurysm formation. It simulates bacterial (gangrenous), fungal (favus) or nutritional (exudative diathesis) dermatitis.
Slowing growth rate as is done in breeders (by restriction of light or feed), and genetic selection of birds that are less susceptible is helpful.
Deep pectoral myopathy
Enzyme level linked to green muscle disease in poultry
After more than a decade of research into an increasingly common and costly broiler condition known as green muscle disease, a team of poultry scientists at Auburn University has identified a blood enzyme that could give breeders a noninvasive tool to screen birds for susceptibility to the disease.
Conditions affecting broiler meat quality
Professor Fernando Rutz of the Federal University of Pelotas in Brazil reviewed the major quality issues relating to muscle development of broilers at the 2015 Alltech Symposium in Lexington, KY.