Search results
Results From The WOW.Com Content Network
Double-muscled cattle are breeds of cattle that carry one of seven known mutations that limits and reduces the activity of the myostatin protein. Normally, myostatin limits the number of muscle fibers present at birth, and interfering with activity of this protein causes animals to be born with higher numbers of muscle fibers, consequently augmenting muscle growth.
The double-muscling phenotype is a heritable condition resulting in an increased number of muscle fibres (hyperplasia), instead of the (normal) enlargement of individual muscle fibres (hypertrophy). [6] This particular trait is shared with another breed of cattle known as Piedmontese.
The active-myostatin gene acts as a "governor" on muscle growth; myostatin is a protein that instructs muscles to stop growing. In effect, when inactive, as it is with Piedmontese cattle, it no longer prevents muscle development which is what allows for the hypertrophic condition sometimes referred to as "double muscling". [7]
Myostatin-related muscle hypertrophy is a rare genetic condition characterized by reduced body fat and increased skeletal muscle size. [1] Affected individuals have up to twice the usual amount of muscle mass in their bodies, but increases in muscle strength are not usually congruent. [ 2 ]
Studies of double-muscled cattle [49] [50] identified natural mutations of the myostatin gene which produce inactivated proteins that are unable to control muscle development. In Belgian Blue and Piedmontese cattle this causes an increase in muscle mass of 20–25%.
Myostatin is a myokine that is produced and released by myocytes and acts on muscle cells to inhibit muscle growth. [7] Myostatin is a secreted growth differentiation factor that is a member of the TGF beta protein family. [8] [9] Myostatin is assembled and produced in skeletal muscle before it is released into the blood stream. [10]
Myostatin inhibitors are a class of drugs that work by blocking the effect of myostatin, which inhibits muscle growth. In animal models and limited human studies, myostatin inhibitors have increased muscle size. They are being developed to treat obesity, sarcopenia, muscular dystrophy, and other illnesses.
In cattle, certain growth features are controlled by recessive genes which have not so far been controlled, complicating breeding. [11] One such trait is dwarfism; another is the doppelender or "double muscling" condition, which causes muscle hypertrophy and thereby increases the animal's commercial value. [11]