1. The present study aimed to evaluate breast muscle quality and muscle myofibre density in two broiler genotypes given three dietary protein feeding regimes.

2. A total of 1440 Ross 308 and 708 broilers (720/genotype) were given one of three dietary protein regimes (Low: 192, 166 and 155 g/kg, Control: 229, 199 and 182 g/kg and High: 266, 235 and 207 g/kg for starter, grower and finisher diets respectively). On d 21 and 42, initial protein solubility, DNA and myofibre density were determined. On d 42, breast meat samples were collected for meat quality analyses.

3. There were no genotype effects on pH₂₄, L*, a* or b* values. Thawing loss was higher in meat from the 708 than the 308 genotype.

4. Broilers given the low protein feeding regime had highest carcase fat, lowest pH₂₄ and palest meat. The low regression coefficients between dietary protein content and changes in pH₂₄ and lightness, however, demonstrated that dietary protein was not the principal factor influencing these traits.

5. Although sarcoplasmic protein solubility was similar among protein feeding regimes on d 21, the highest sarcoplasmic protein solubility on d 42 was in broilers on the high protein regime.

6. Myofibre density was highest in meat from broilers given the low protein regime.

7. It was concluded that dietary-protein content contributes significantly to both protein solubility and myofibre density.