Possible use of an indicator muscle in future breeding experiments in domestic fowl.

Domestic fowl were chosen for different body weights in descending order of size, viz. Tetra, Rhode Island Red/Light Sussex cross, White Leghorn and Bantam. The numbers and sizes of fibres in various muscles were determined by quantitative histology, and fibre number was also estimated by DNA measurement. In contrast to the situation in mammals, fibre size (diameter) was of greater importance than fibre number in determining muscle size. Biochemical measurement of DNA content in a muscle was not a reliable estimate of cell number without histological verification. It is suggested that the anterior latissimus dorsi muscle could be used as an indicator muscle in future selective breeding programmes for fibre number because of its fibre arrangement and accessibility.