I have asked myself this question over the years and wondered of the importance of this liquid. After watching Food For Louis after he drank blood, he made the comment that the cows blood tasted like it should be a health drink. I think he is probably on the something.
If you regard Chinese Medicine, you will find they associate the consuming of other animal parts with feeding your own. Such as eating the heart will feed your heart. Well, drinking blood cannot be much different. People can very likely feed and improve their own blood by consuming other animals blood. From the health perspective, consuming blood makes a lot of good sense.
Why are people so adamant at saying that the consumption of blood is bad? Because the Western medicine doctors want to have us believe that drugs and surgery are the better anwers for improving health. Even though, what they do is draw a lot of our blood.
When I saw the elk farm in Forks, WA, I thought of The Twilight books where the vampires switched from consuming human blood to animal blood. I have never seen so many elk in one spot together before. You could really imagine the Vampire family harvesting the animals blood for their own desires in the Forks, WA area.