Over the past decades, broilers have been growing at an increasing rate. This is not only due to changes in their genetic composition but also through improvement of housing, nutrition and management. The increase in the breast meat weight of broilers is particularly striking. As the slaughter weight of broilers increases, in combination with the growth curve required to achieve this slaughter weight, we are seeing several muscle abnormalities which influence the quality. Robert Jan Molenaar at Royal GD discusses the main abnormalities that often only become apparent during the slaughter process.
Extract:
‘Muscle Abnormalities in Broilers’
Deep pectoral myopathy
Deep pectoral myopathy (DPM) is also known as green muscle disease. This is not a form of contagious disease, but rather a wasting of the deep pectoral muscle due to blood supply issues.
How does it occur?
The deep pectoral muscle is located between the breastbone and the breast meat (the superficial pectoral muscle) and is used when chickens move their wings. Broilers are extremely muscular and this muscle therefore has little space for expansion. If the broiler flaps its wings energetically, there is extra blood supply to this muscle. This is the body’s way of ensuring that the muscle has sufficient oxygen supply and sufficient disposal of waste products. All that extra blood results in the muscle becoming temporarily expanded. When the muscle contracts, it is smaller than when in a relaxed state. If the muscle then swells excessively in this state due to the extra blood, the situation can arise whereby the muscle no longer has enough space to relax normally. The pressure will then increase to such an extent that the blood vessels around the muscle are compressed, stopping the blood from flowing out of the muscle. No new blood can be pumped in, resulting in myopathy of the muscle tissue due to a lack of oxygen and the accumulation of waste products. This may colour the muscle tissue green, hence the name green muscle disease.
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