Skeletal muscle fibre growth and growth associated myopathy in the domestic chicken

Vicky E MacRae*, Michael Mahon, Sally Gilpin, DA Sandercock, MA Mitchell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

90 Citations (Scopus)


1. Genetic selection of broilers may have pushed muscle fibres to their maximum functional size constraints. Broiler (B), female great-grandparent (GGP) and layer (L) lines were weighed, blood sampled and killed from 5 to 25 weeks of age.
2. At 25 weeks, Pectoralis major (Pm) fibre size reached by the B (65.9 mm) and GGP (59.8 mm) were 1.5 times greater than the L (38.1 mm). In the B and GGP lines, fibre growth of the Pm markedly exceeded that of the Biceps femoris (Bf) muscle. However, in the L line, fibre growth of the Pm and Bf muscle was comparable. Connective tissue content was generally higher in the Bf than in the Pm of all lines.
3. Centralised nuclei were observed predominantly in Pm, and may regulate fibre size. Both large muscle fibres and inadequate capillary supply may induce metabolic stress in B and GGP lines due to the large diffusion distances for oxygen, metabolites and waste products. 4. Enzyme markers of muscle damage (creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate amino transaminase (AST)) and histopathological analysis of Pm and Bf indicated greater myopathy in B and GGP vs L.
5. Regenerative processes were associated with oestrogen secretion. Reduced CK and LDH preceded egg yolk precursor production and increased calcium uptake for eggshell synthesis in all three lines. Oestrogen may stimulate muscle fibre regeneration and recovery as a myo-protective adaptation to potentially detrimental changes in calcium economy during egg production.
Original languageEnglish
Pages (from-to)264-272
Number of pages8
JournalBritish Poultry Science
Issue number3
Publication statusPrint publication - Jun 2006
Externally publishedYes


  • Broiler chicken
  • Layer chicken
  • Skeletal muscle pathology
  • Histopathology
  • Oestrogen
  • Myo-protection
  • Pectoralis major
  • Biceps femoris
  • Muscle fibre number
  • Muscle fibre growth
  • Creatine kinase


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