Paradigm of deep pectoral myopathy in broiler chickens

Abstract

Deep pectoral myopathy (DPM) of musculus pectoralis minor is an anomaly observed in gallinaceous poultry. To date its cases have been reported in adult pedigree turkeys and hens and in recent years also in broiler chickens. This degeneration is manifested in an abnormal appearance of breast muscles, with changes in colour from pink to green, as well as changes in the texture of the muscle tissue. The anomaly is found most frequently in genetic lines of chickens characterised by dynamic weight increment in the rearing period as well as a considerable increase in the proportion of pectoral muscles. The mechanism for the development of myopathy is already well known. It is related with ischemic necrosis initiated by rapid physical activity of birds, which mobilises pectoral muscles, normally relatively inactive in modern intensive animal management systems. Absence of symptoms manifested in vivo results in a situation when muscles affected by myopathy are identified only during carcass dissection. An increasing number of cases of this anomaly, as well as the fact that necrotic lesions affect valuable carcass elements make this problem one of great importance for chicken growers and abattoirs and poultry processing plants. In recent years DPM cases have been reported with increasing frequency in the USA, Italy, Greece and Bulgaria in commercial genetic lines. In Poland, a number of DPM cases have been recorded in large populations in flocks of five to seven week old chickens from 0.02% up to 1.9%. Risk factors for the occurrence of DPM on farms have been analysed, and are considered mainly due to intensive wing flapping. Identification of these factors may result in better farm management and constitute the basis for the DPM prevention system. A solution to this problem is not available currently.

Keywords::

• chicken
• musculus pectoralis minor
• myopathy
• aetiology
• induction
• prevention