Re: how does a cow make so much muscle mass when eating grass?

Baisically cattle can do this because they have specialized stomach 
compartments that allow them to convert carbohydrates into amino acids.  
Cattle or ruminants have 4 seperate stomach compartments that are 
specially designed and developed to do this.  In the rumen the food is 
fermented by microbes. During digestion carbohydrates including 
cellulose 
are broken down into fatty acids which is used as energy for maintenance, 
reproduction, growth and milk production.  About 40 to 75% of their food 
is conveted to ammonia and amino acids.  Specialized rumen microbes 
convert the ammonia and organic acids into amino acids and even into 
their 
necessary vitamins. The amount of free range excercise and genetics 
would 
determine their size and muscle mass. We humans would be deficient on 
such 
a diet and obviously are not built the same way, thank goodness since 
cows 
contribute a significant amount to the greenhouse affect by belching 
gases.
  For more on this go to www.extension.umn.edu  Hope 
that 
helps.