Altered Sarcomeric Structure and Function in Woody Breast Myopathy of Avian Pectoralis Major Muscle

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Liu , J , Puolanne , E , Schwartzkopf , M & Arner , A 2020 , ' Altered Sarcomeric Structure and Function in Woody Breast Myopathy of Avian Pectoralis Major Muscle ' , Frontiers in Physiology , vol. 11 , 287 . https://doi.org/10.3389/fphys.2020.00287

Title: Altered Sarcomeric Structure and Function in Woody Breast Myopathy of Avian Pectoralis Major Muscle
Author: Liu, Jiao; Puolanne, Eero; Schwartzkopf, Matthias; Arner, Anders
Contributor: University of Helsinki, Department of Food and Nutrition
Date: 2020-04-09
Language: eng
Number of pages: 11
Belongs to series: Frontiers in Physiology
ISSN: 1664-042X
URI: http://hdl.handle.net/10138/324858
Abstract: The "Woody" or "Wooden" breast disease is a severe myopathy of pectoralis major muscle recently identified within rapidly growing broiler lines all around the world with a prevalence rate around 20%, or even higher. Although of significant ethical and economic impact, little is known regarding the structural and functional aspects of the contractile apparatus in the woody breast muscle. The aim of the present study was to determine physiological properties of the contractile system in the morphologically intact muscle fibers of focally damaged woody breast in comparison with normal muscle fibers to gain insight into the muscle function of the animal and possibly mechanisms involved in the disease development. Muscle samples were taken from woody breast (non-lesioned areas) and normal breast muscles from broilers. Length-tension curves, maximal active stress, maximal shortening velocity, calcium sensitivity, rate of tension development, lattice spacing and muscle biochemical composition were investigated on single skinned fibers. Sarcomeres of woody breast fibers were more compliant, which is very likely related to the wider spacing (18% wider compared to controls) between thick and thin filament. No differences were found in optimal sarcomere length (2.68 +/- 0.04 vs. 2.65 +/- 0.05 mu m) nor in maximal active stress (116 +/- 17 vs. 125 +/- 19 mN mm(-2)). However, woody breast fibers had less steep descending arm as shown in length-tension curve. Woody breast muscle fibers had 40% bigger sarcomeric volume compared to controls. Content of contractile proteins (myosin and actin), and maximal shortening velocity were unchanged indicating that the growth in woody breast muscle fiber was associated with synthesis of new contractile units with unaltered kinetics. Calcium sensitivity was decreased in woody breast muscle fibers significantly. In conclusion, the results show that the rapid growth of muscle in woody breast disease is associated with significant structural and functional changes in the pectoralis major musculature, associated with alterations in the mechanical anchoring of contractile filaments.
Subject: avian muscle
hypertrophy
muscular dystrophy
muscle disease
sarcomere
SKELETAL-MUSCLE
GENE-EXPRESSION
QUALITY TRAITS
MEAT QUALITY
MYOSIN HEAVY
FIBERS
GROWTH
FORCE
MYODEGENERATION
ACTIVATION
1184 Genetics, developmental biology, physiology
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