Theo, that is interesting. 100 lbs of hay plus average of 63.75 pounds of water turns into 116.6 pounds of waste. Thus, they are using about 47 pounds of the feed for their body. I wonder how much actually stays to grow and fatten. After all, they will burn up some of it.
I also wonder how many cows there are in the US to find out how much poop is created on a daily basis. Staggering thought!