2009 was a bad year for, uh, vampire cows. That was the year that the FDA outlawed the use of dead cow blood and blood products for feeding live cows and calves. Brain and blood matter was often ground up into cattle feed and calves were weaned with synthetic milk that contained cow's blood. Because feeding cows the brains and blood of other cows is an excellent way to spread mad cow disease, this practice was stopped. However, poultry and pig feed can still be made with cow remains, so there is a chance a busy farmer might mix up the feed and return cows to their (un)natural vampirical practices.