A team of scientists at the University of Saskatchewan examined the development and causation of cardiomyopathy in broilers selected for high growth rate compared to a slow-growing broiler strain and leghorn pullets. Advanced techniques were applied to investigate the condition including transmission electron microscopy and synchrotron Fourier transform infrared micro-spectroscopy supplementing conventional light microscopy.
The principal lesion in fast-growing broilers involved conformational changes within the cardiomyocytes (heart muscle cells). Affected fast-growing broilers showed accumulation of misfolded protein in the cardiomyocytes. Apparently affected heart muscle tissue cannot dispose of damaged protein due to dysfunctional phagosome and proteosome activity. Progressive damage to cardiomyocytes in the left ventricle eventually leads to dilation terminating in cardiac failure.
Dilated cardiomyopathy is distinct from right-heart failure also encountered in rapidly growing broilers. This condition appeared about 25 years ago and was associated with pulmonary congestion but was characterized by dilation of the right ventricle.
Additional studies will be required to elucidate the factors leading to the cellular changes in cardiac muscle. Evidently there is a genetic component but obviously epigenetic factors including environment and nutrition may be involved.