Green muscle disease (GMD), or deep pectoral myopathy (DPM), is a non-infectious degenerative muscle condition in commercial broilers and turkeys. Rising incidence in the deboning sector reflects decades of selection for heavier market weights and greater breast meat yield (Bilgili and Hess, 2002).
How the Injury Develops
The minor pectoral, or breast tender, is enclosed in a rigid inelastic fibrous sheath between the sternum and the major breast fillet. During wing flapping the muscle expands by up to 25 percent in volume (Aviagen, 2025), raising intramuscular pressure until oxygen delivery stops. Ischemic necrosis follows. The characteristic green discoloration develops over subsequent days as hemoglobin and myoglobin break down into bile salts.
Birds show no clinical signs at any stage. Lesions are invisible through the skin and undetectable at ante-mortem inspection (Tabler et al., 2014). GMD surfaces only at deboning in the processing plant.
What Triggers Wing Flapping
Risk increases after 35 days of age, when breast muscle mass is largest (Aviagen, 2025). Documented triggers include sudden increases in light intensity, abrupt lighting program changes, machinery noise, fast human movement through the house, and rough catching procedures (Bilgili and Hess, 2008; Tabler et al., 2014).
Applying photostimulation abruptly can trigger a flock-wide startle response. Aviagen (2025) warns against sudden increases below 3 lux and recommends dawn-to-dusk dimmer programs.
Chronically stressed or flighty flocks carry higher risk. Persistent weight deviations from breed targets, or widening variability within a flock, can signal environmental stress that primes birds to react strongly to disturbances. Continuous automated live weight monitoring makes these deviations visible early.
Weight trends across grow-outs stored in BAT Cloud help managers identify recurring stress factors before they compound.
Tight flock uniformity also supports confident adherence to breed-specific lighting schedules. Regular hands-on weight assessment confirms whether weight distribution is tightening or widening as the flock develops.
Is It Safe to Eat Chicken With Green Muscle Disease?
This question reaches consumers whenever green chicken meat appears at retail or at the table. Because GMD is a physiological injury rather than the result of any pathogen or toxin, it presents no food safety risk. Aviagen (2025) confirms the condition carries no public health significance beyond the aesthetic appearance of the tissue.
Condemned tenders are removed at the processing plant, and hemorrhage from a damaged tender can also stain the adjacent fillet, requiring further trimming. Projected losses from condemned tenders and fillet trimmings approached $7,000 per week for a plant processing one million heavy broilers (Bilgili, 2011). GMD is a commercial cost, not a public health concern.
Reducing Incidence Through Management
No treatment exists for affected birds. Prevention depends on management that limits wing-flapping events (Aviagen, 2025; Tabler et al., 2014). Walk slowly through the house. Raise light intensity gradually with a dimmer. Minimise machinery noise in the weeks before processing. Keep catching calm and avoid feed withdrawal exceeding four hours.
Good flock uniformity is a practical lever producers already have. The BAT2 Connect automatic scale provides continuous live weight data that keeps flock performance visible throughout the production cycle.
The BAT1 manual poultry scale is well suited to the regular sampling sessions that build the uniformity picture needed to apply lighting schedules with confidence.
GMD management depends on quiet, consistent husbandry from placement to catch.
References
1.) Aviagen. 2025. Deep Pectoral Myopathy: Reducing the Incidence in Broiler Flocks. Aviagen Brief, Version 2. https://aviagen.com/assets/Tech\_Center/Broiler\_Breeder\_Tech\_Articles/English/AviagenBrief-Deep-Pectoral-Myopathies.pdf
2.) Bilgili, S. F. 2011. Finding answers to green muscle disease in poultry. WATTPoultry. https://www.wattagnet.com/articles/8761-finding-answers-to-green-muscle-disease
3.) Bilgili, S. F., and J. B. Hess. 2002. Green muscle disease in broilers increasing. World Poultry 18(4):42–43.
4.) Bilgili, S. F., and J. B. Hess. 2008. Green muscle disease: Reducing the incidence in broiler flocks. Aviagen Brief, March 2008.
5.) Dickinson, E. M., J. O. Stephens, and D. H. Helfer. 1968. A degenerative myopathy in turkeys. Proc. 17th West. Poult. Dis. Conf., University of California, Davis.
6.) Richardson, J. A., J. Burgener, R. W. Winterfield, and A. S. Dhillon. 1980. Deep pectoral myopathy in seven-week-old broiler chickens. Avian Dis. 24:1054–1059.
7.) Tabler, T., F. D. Clark, J. R. Moyle, M. Farnell, and J. Wells. 2014. Deep Pectoral Myopathy (Green Muscle Disease) in Broilers. Mississippi State University Extension Service, Information Sheet 1976. https://extension.umd.edu/sites/extension.umd.edu/files/2022-01/IS1976%20Deep%20Pectoral%20Myopathy.pdf