Edinburgh Research Archive logo

Edinburgh Research Archive

University of Edinburgh homecrest
View Item 
  •   ERA Home
  • Royal (Dick) School of Veterinary Studies
  • Royal (Dick) School of Veterinary Studies thesis and dissertation collection
  • View Item
  •   ERA Home
  • Royal (Dick) School of Veterinary Studies
  • Royal (Dick) School of Veterinary Studies thesis and dissertation collection
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Postnatal development of porcine skeletal muscle

View/Open
DaviesAS_1973redux.pdf (25.99Mb)
Date
1973
Author
Davies, A. S.
Metadata
Show full item record
Abstract
 
 
The manner in which skeletal muscle of the pig adapts to meet the changing mechanical and metabolic demands of an increase in body weight during postnatal growth was studied using two different methods.
 
(1) Histochemical profiles of individual muscle fibres were established using the myosin ATPase, succinate dehydrogenase (SDHase) and glycogen phosphorylase (GPase) reactions. Samples of longissimus and diaphragm muscles from a series of 18 Large White pigs between birth and 60 kg liveweight, and from a series of 16 Large White pigs of mean liveweight of 93 kg, were used.
 
In both muscles, the number of fibres low in myosin ATPase activity increases with growth, and these fibres are grouped into bundles. In m, longissimus, the estimates of the total fibre population and the number of myosin ATPase low bundles in a complete transverse section of the muscle remain constant, while the mean number of myosin ATPase low fibres per bundle increases from one at birth to 3'2 at 93 kg liveweight. Whereas the complete transverse sectional area of the muscle increases in proportion to the 2/3 power of the body weight, the area occupied by myosin ATPase low fibres increases in direct proportion to the body weight. This observation suggests the mechanism by which larger animals are supported without a relative increase in their muscle mass. Some histcchemical evidence was obtained that this is achieved by a transformation of the physiological properties of certain fibres.
 
The diaphragm of smaller pigs contains a greater proportion of a myosin ATPase high, SDHase high and GPase low fibre type than that of more mature pigs. After initial neonatal differentiation, the muscles studied do not change their proportion of SDHase high fibres during growth,
 
In both longissimus and diaphragm, the mean transverse sectional areaof myosin ATPase high fibres is greatest when the SDHase activity is low. Also, the mean transverse sectional area of SDHase high fibres is greatest when the myosin ATPase activity is low, but this difference is significant only for the diaphragm,
 
(2) Eighteen female pigs of both the Pietrain and Large White breeds, from birth to 72 kg liveweight, were dissected, and the major tissues were weighed. The growth of fat, muscle and bone, relative to carcass growth, were compared for both breeds. Fat is the fastest developing tissue; fat and muscle grow at a rate higher, and bone at a rate lrwer, than overall carcass growth. The musclesbone ratio increases during the growth interval studied.
 
Growth changes in the distribution of muscle and bone were studied by weighing these tissues after separation into 93 muscle units and 10 b^ne units. The pattern of growth of both these tissues can be described as an increasing craniocaudal gradient axially and an increasing distcproximal gradient in the limbs. It is proposed that these gradients are an adaption to enhance the animal's propulsive force. The cardiac muscle:skeletal muscle ratio decreases with growth.
 
Of the major tissues, only the growth of bone is significantly different between the two breeds; this tissue develops faster relative to carcass growth in the Large White. When the breeds are compared at the same body weight, the weight of muscle is greater in the Pietrain over the entire growth range studied. Musclejbone ratios, compared at the same values of total muscle plus bone, are higher for the Pietrain. There are no significant differences between the muscle:bone ratios of the Large Whites used in the present study and the Large Whites dissected by McMeekan ever 30 years ago.
 
A comparison of the difference in tissue distribution between the two breeds shows that growth gradients for muscle are accentuated in the Pietrain. Although the weight of muscle in all regions is higher in the Pietrain at birth, only the weights of abdominal and femoral muscles and m. longissimus are significantly higher in the Pietrain when these weights are compared in pigs of 60 kg body weight. No difference in bone distribution is apparent between the breeds. Consequently, although the ratio of brachial muscle weight to humerus weight is higher for the Pietrain, in pigs of 60 kg body weight the difference between the breeds is very much greater for the ratio of femoral muscle weight to femur weight. At 60 kg body weight, the heart of the Large White is heavier; the cardiac muscle{skeletal muscle ratio of the Large White is higher over the entire growth range studied.
 
Since the proportions and distribution of the skeletal muscle, cardiac muscle and bone of the Pietrain are an exaggeration of the changes observed in the Large White during growth, it is concluded that the Pietrain is more mature at the same body weight than the Large White, and that a genetic control of muscle distribution is possible.
 
A study of samples of m. longissimus, removed from the muscle without restraint to contraction, suggests that the greater development of this muscle in the Pietrain is due to relative hypertrophy of a similar number of component fibres. No difference between the breeds is observed in the proportion of fibre types, as determined by the myosin ATPase reaction.
 
URI
http://hdl.handle.net/1842/30155
Collections
  • Royal (Dick) School of Veterinary Studies thesis and dissertation collection

Library & University Collections HomeUniversity of Edinburgh Information Services Home
Privacy & Cookies | Takedown Policy | Accessibility | Contact
Privacy & Cookies
Takedown Policy
Accessibility
Contact
feed RSS Feeds

RSS Feed not available for this page

 

 

All of ERACommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsPublication TypeSponsorSupervisorsThis CollectionBy Issue DateAuthorsTitlesSubjectsPublication TypeSponsorSupervisors
LoginRegister

Library & University Collections HomeUniversity of Edinburgh Information Services Home
Privacy & Cookies | Takedown Policy | Accessibility | Contact
Privacy & Cookies
Takedown Policy
Accessibility
Contact
feed RSS Feeds

RSS Feed not available for this page