Properties of muscles from chickens with inherited muscular dystrophy

Inherited muscular dystrophy of the chicken is an abnormality affecting the normal development and function of fast-twitch skeletal muscles. Several different strains of dystrophic chickens have been developed by selection for high lipid content in the pectoralis muscle and early onset of the disorder or by outcrossing the original New Hampshire stock into an inbred White Leghorn breed. The purpose of this study was to determine whether fast-twitch dystrophic muscles differ in expressed properties within the same bird and to examine the differences in gene expression between dystrophic New Hampshire and White Leghorn breeds. The biochemical and physiological properties examined were lactate dehydrogenase and acetylcholinesterase activities, total lipid content, muscle fiber diameter and electromyographic insertion activity. Results showed that fiber diameter and lipid levels were different in muscles within individual birds of two dystrophic lines and that the dystrophic gene causes rapid fiber atrophy and high lipid content in the White Leghorn breed. In addition, differences in lactate dehydrogenase activity and electromyographic patterns were found between two dystrophic lines. The results suggest that the expressed properties differ within each muscle of the dystrophic bird and that the expression of the dystrophic genes is dependent upon the nature of the genetic background of the breed.