It depends entirely on the nature of the ritual, and the significance of the blood. As has been stated above, blood is the living river, the shared gift of all our ancestors. There is power there that can’t be traded out.
BUT, and it’s a right big but, that living essence isn’t unique to platelet-carrying blood-havers. A lot of Grecian Witchery allows for the substitution of Pomegranate Juice for blood. Our plant and animal brethren are every bit as connected to that endless current as we are, and their vital essence is no less valuable.
The difference is that your own blood is uniquely yours to give away in offering. If you want to get that kind of value from the vital essence of something or someone else, it has to be given to you, or properly paid for. Otherwise, it means next to nothing.