Added to what the other guy said (that it’s grazing land that HAS to fallow whether used or not), that 77% number ALSO counts the waste from crops we’re growing for humans, waste that would be going to an incinerator if they weren’t going to a cow or pig.

Very few (if any, depending how you define the breakdown) crops are grown with animals as their focus. It just so happens that’s how much of those crops we cannot digest.