Understanding Green Muscle Disorder in Broilers

In the world of poultry farming, green muscle disease is often misunderstood. First and foremost, it’s essential to clarify that this condition is not classified as a disease but rather a disorder characterized by muscle degeneration. While it predominantly affects Cornish-cross broilers, it has been recognized since 1968, making it an age-old concern that is also highly preventable.

What is Green Muscle Disease?

Initially discovered in broad-breasted turkeys, green muscle affects heavy-breasted broilers, particularly cockerels, more frequently than pullets. The disorder typically becomes apparent post-slaughter when the tender – situated at the deepest part of the breast muscle next to the breastbone – appears discolored. This inner muscle, known as deep pectoral muscle, is technically termed deep pectoral myopathy (DPM).

The condition arises from broilers being selectively bred for excessively large breast muscles, which can constitute up to 25% of a bird’s total body weight. Additionally, their sedentary lifestyle, largely spent eating, leads to inadequate muscle exercise and blood circulation.

Causes of Green Muscle Disease

The deep pectoral muscle is crucial for wing elevation and is confined within a rigid sheath and the breastbone. When broilers flap their wings, blood flow to this muscle increases, causing it to expand. However, if wing flapping persists, the muscle may become constrained, leading to blood flow cessation.

Prolonged deprivation of oxygen results in the tender bruising, atrophying, and potentially dying. Depending on the timing of slaughter relative to wing flapping incidents, the affected muscle may exhibit colors ranging from bloody to yellowish or even a green hue.

Interestingly, green muscle disease tends to affect heavier broilers, particularly those raised for roasting as opposed to those harvested early for frying. It is also more prevalent in cooler climates, where broilers tend to grow more rapidly.

Furthermore, pastured broilers may face additional challenges, as they are exposed to various stimuli that may provoke sudden wing flapping, such as predators or loud machinery.

Treatment and Safety of Affected Meat

Green muscle disease, along with white striping and woody breast—other forms of breast myopathy—does not show external signs until after slaughter, and it has not been linked to any infectious agents. Instead, these conditions are symptoms of metabolic dysfunction in muscle cells and therefore are not treatable.

Despite any concerns, meat affected by green muscle is safe to eat, as it is not the result of pathogenic bacteria. The discoloration may render it unappealing, and the texture can be firm and fibrous. Nonetheless, if trimmed appropriately, the unaffected portion can be cooked and enjoyed as usual.

Preventing Green Muscle Disease

Prevention is key, as the condition can arise from just one significant bout of wing flapping. More commonly, it is the product of repeated minor incidents. Effective preventive measures include:

• Preventing pets and children from chasing broilers.
• Avoiding catching or carrying birds by their wings or legs.
• Not providing perches that encourage wing flapping.
• Minimizing overcrowding to reduce stress and jostling.
• Ensuring adequate feed and water stations based on flock size.
• Maintaining calm and gentle interactions with the flock.

Alternative options to the typical white Cornish broilers include colored hybrids such as Color Yield, Freedom Ranger, and Kosher King, as well as heritage breeds like Delaware, New Hampshire, and Plymouth Rock, which grow more slowly and are less susceptible to breast myopathies.

Moreover, Naked Necks, while not a heritage breed, also excel as meat birds and possess advantages during processing thanks to their sparse plumage. These breeds exhibit moderate to slow growth rates, mitigating the risk of developing the aforementioned myopathies.

Through diligent management of your backyard broilers to reduce stress, you can enjoy peace of mind and ensure that you and your family will not face the dilemma of serving green chicken meat.

Stay informed and take care of your flock!

Source: The Cackle Hatchery