When you slaughter a full size cow you get around 440 lbs of beef or meat from the cow.
The rest of the weight is in fat, bones, brain etc.
Most cows are slaughtered by the time they reach 30 to 44 months of age.
The older the cow gets the less quality the meat is from the cow so it's important to fatten up the cow as soon as possible and slaughter the cow before it gets past 48 months of age.
The longer you wait to slaughter the cow the more tough the meat would be.
So that's why most meat processors or cow farmers slaughter the cows before 48 months of age.
Around 200 lbs of ground beef come from one cow and the rest of the 220 or so lbs of meat comes from meat cuts like steaks, roasts, ribs, brisket, tenderloin etc.