WATT PoultryUSA - May 2011

Green Muscle Disease in chickens:

➥Deep pectoral myopathy, also called Green Muscle Disease or Oregon Disease, refers to necrosis and atrophy of the minor pectoral muscles (i.e., supracoracoideus or breast tenders) of poultry. The DPM lesions often affect both tenders and vary in severity (size of the necrotic area and color), progressing from a pinkish hemorrhaging to a gray-greenish discoloration. The photographs displayed here represent the time-course of DPM lesions on chilled broiler chicken carcasses, induced through “ encouraged wing flapping” one to 11 days prior to processing. These pictures provide a visual reference as to the timing and nature of environmental and management factors triggering excessive wing exertion. During the early stages of the condition (one to three days), the muscle is pale, swollen and covered by a hemorrhagic membrane. Subsequently (five to 11 days), the muscle turns yellow-green with the breakdown of hemoglobin to bile pigments. The cut muscle appears dry, and muscle fibers separate more easily than is seen in normal muscle. In older birds, affected muscles can atrophy with breast appearing sunken. When the Auburn University researchers attempted to induce DPM with the EWF technique prior to about 35 days of age, no lesion was observed. It was determined that DPM must be caused by wing flapping at least 24 to 48 hours before slaughter, since tenders take this long to develop the discolored lesions.