ive been interested in myostatin inhibition for a while
this study is worth a look
the effects it has on Belgium blue double muscle cattle is amazing (thats their real name due to the fact they are homozygous for the gene that suppresses myostatin)
this was achieved simply by selective breeding over many generations and they look freakishly muscular. also they carry next to no adipose tissue!
as mentioned above this is also great for meat and what they are primarily bred for
ie greater feeding efficiency. a tender piece of meat is created by the muscle of the cow not been used much in its life.
with these animals they can remain inactive but still produce huge amounts of meat
the extra muscle in belgium blues according to that study is totally due to hyperplasia and not hypertrophy. at birth these cattle contain nearly twice as many muscle fibers as normal cattle.
but as good as this is as bill mentioned its not easy changing the DNA in most of your bodies cells