A comparison of the myo-protective effects of sexual maturity in female chickens from lines selected for divergent production traits.

Vicky E Cooke*, Ailsa J Carlisle, MA Mitchell, DA Sandercock

*Corresponding author for this work

Research output: Contribution to journalMeeting Abstractpeer-review


Genetic selection for improved growth rate in broiler chickens is associated with an age related spontaneous myopathy indicated by elevations in plasma activity of the intracellular muscle enzyme creatine kinase (CK). However, at sexual maturity in female birds there is a significant reduction in plasma CK. This apparent myo-protective effect of oestrogens has been replicated in immature broilers by administration of oestradiol. The present study has compared the alterations in skeletal muscle cell membrane integrity associated with sexual maturity in female birds from 3 lines selected for growth or reproductive performance, a commercial broiler (B), female great grandparent broiler (female line - GGP) and a commercial laying (L) line. Blood samples were obtained from 4 different birds of each line at intervals between 4 and 26 weeks of age. Plasma activity of CK, concentrations of plasma calcium (Ca) and the egg yolk precursors (EYP) very-low density lipoprotein (as triglyceride or TG) and vitellogenin (as zinc or Zn) were determined by spectrophotometry. Above 16 weeks of age plasma TG, Zn and Ca concentrations increased significantly (p<0.001). These oestrogen dependent responses differed between lines (p<0.001) the EYP and plasma calcium concentrations being greater in the laying line hens (p<0.001). Plasma CK activity increased with age, peaking before sexual maturity, in all birds and differed between lines (p<0.01). Muscle damage was greater in those lines more heavily selected for improved growth rate. The elevations of the plasma indices of the onset of sexual maturity were coincident with significant reductions (p<0.05) in plasma CK activities in all lines. It is proposed that these observations are consistent with a fundamental myoprotective function of endogenous oestrogens. It is hypothesised that this is an adaptation to egg laying induced alterations in calcium uptake and homeostasis which otherwise might compromise tissue function.
Original languageEnglish
Article numberabstract 247
Pages (from-to)58
Number of pages1
JournalPoultry Science
Issue number1
Publication statusPrint publication - 2002
Externally publishedYes
Event91st Poultry Science Association Annual Meeting 2002 - University of Delaware, Newark, United States
Duration: 11 Aug 200214 Aug 2002


  • Genetic selection
  • Growth rate
  • Idiopathic myopathy
  • Broiler chicken
  • Laying hen
  • Broiler great grandparent line
  • Skeletal muscle pathology
  • Oestradiol
  • Creatine kinase
  • Plasma triglyceride
  • Plasma zinc
  • Plasma calcium
  • Sexual maturity
  • Endogenous oestrogen
  • Calcium homeostasis


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