Muscle Disorders

Factory-farmed turkeys gain so much weight during their short lives that their hearts often cannot support their huge bodies. The following table compares the weight and muscle mass of turkeys at 25 weeks:(47)

Weight Breast
Traditional turkey 5.3kg 0.52kg
Modern turkey 19.22kg 3.04kg

Turkeys gain so much weight in a short amount of time that the relative weight of the heart decreases from 0.59% to 0.32% in factory-farmed turkeys. However, it stays constant in 'traditional' turkeys.(48) This excessive weight gain will cause muscle growth to exceed the capacity of the heart, perpetuating poor capillary supply and muscle fibre degeneration in factory-farmed birds.(49)

Romvari et al state that:

The link between growth rate and susceptibility to muscle disorders becomes more and more evident. Muscle abnormalities, such as deep pectoral myopathy, have long been recognised and appear to be a consequence of the inability of the cardiovascular system to meet the oxygen demands of the rapidly growing tissues, particularly under stress.(50)

Intensive rearing conditions make young turkeys susceptible to dying of heart disease, as the blood vessels become clogged causing organ failure.(51) Mortality is generally 0.5-2.0 per cent or sometimes higher and is thought to be due to an "inadequate or inappropriate cardiac response to exercise, resulting in hypotension, vasodilation, arrhythmias, and sudden death".(52)