Green Muscle Disease is a hidden problem in mode-day broiler chickens. Green Muscle Disease (or Oregon Disease) is a common name given to a degenerative muscle disease known as Deep Pectoral Myopathy (DPM). The condition is characterised by necrosis and atrophy of the tenders (i.e. supracoracoideus or minor pectoral muscles). The lesions often affect both tenders and vary in colour, progressing from a pinkish haemorrhagic appearance to a grey-greenish discolouration as illustrated in Figure 1