Blood offerings are used to venerate and "heat" God`s helper spirits (your ancestral spirits and whatever you call your "spiritual team", i.e. saints, lwa, orisha, avatars, or minor gods & goddesses).
This practice, traditional to indigenous spiritual paths, is misunderstood by the uninitiated. Animal sacrifice is a major reason why religions of the African diaspora are victim to prejudice. People can`t get beyond visions of Fluffy and Fido being tossed into a cauldron whilst chanting "natives" (dressed in feathers and little else) dance about the cruel fire (that and human sacrifice/zombies are all they can see).
Animal sacrifice is based upon cultural systems that emphasize communal unity and the feeding of ancestral spirits, followed by minor deities or "links to the One God". When an animal is sacrificed, it s done for the greater good of the community (or an individual/family within the group, considered an essential to the whole). The spirits feed upon the slaughtered animal`s essence and the community feasts upon it`s corporeal nature.
This event is never random, nor is "just anyone"enabled to do it-it is a special event carried out by a Priest/ess of a certain rank. The animals normally sacrificed are those first world non-vegetarians eat every day-they simply aren`t exposed to "the hard part", or the slaughter.
All of this said, I do not practice blood sacrifice.
Personally, I don`t agree with it. I know the animal has to experience some suffering (in the case of a Native American offering, the wings of a bird must be broken before it`s neck vertebra are severed).
Blood makes modern magicians a bit uncomfortable, aside from practices such as utilizing menstrual blood (in women`s mysteries), and perhaps the pricking of a finger to infuse a magical blend with one`s source of power (or to consecrate a ritual item).
And so I think it unnecessary, within the context of those practicing indigenous religions from a first world perspective. The spirits are given many types of potables, and they will get used to enjoying the "cruelty-free" plentitude you offer them. Again, this is my opinion (and I take my inspiration from Dr. Denise Alvarado and Mambo Sallie Ann Glassman).
Yet I do not deny or disrespect the rights of others in carrying on a tradition, unchanged. Not so long as I continue to consume animal flesh myself (though I actually eat very little in the way of red or white meat...eggs, fish, nuts and soybean products are the way to go, folks...keeps you slim and healthy, too).
And now I get to another undeniable- the fact that a "blood offering" can be very effective in grabbing the attention of a spirit. It heats the spirit, excites them in a specific way. But how to avail myself of this power without cruelty?
You can buy blood at a butcher shop...but not for me.
You can use blood meal from a gardening shop (something I`ve incorporated into certain spells, but not something I`d prefer to use regularly).
But what if you would like to stay away from animal products entirely?
What if you are vegan or vegetarian?
I`ve seen the following gemstones and juices offered as potential substitutes, and they do work well.
They are: garnet, ruby, carnelian, pomegranate, tomato, cranberry and apple cider.
Wine is also an option, of course.
However, I`ve found something that my spirits have liked even better-maguey root.
Maguey root is a Mexican ceremonial herb associated with Mars.
It is mentioned in the Aztec myth of Nanahuatzin,a minor deity at the beginning of time. He became a chief spirit by bringing the Sun to creation. The world was dark and both human beings and animals could not develop without an energy source. After consultation with the other gods Nanahuatzin was chosen to make a sacrifice of the maguey to Huitzilopochtili ("the Left-Handed Hummingbird", the Aztec name for the overriding "One God" or "Great Spirit"). The Gods believed that sacrifice would bring an answer. In making this sacrifice, Nanahuatzin went overboard. He offered not only the reeds of the maguey, but the thorns as well. In doing so he made a bloody mess of himself, and the maguey is now forever tinged with the life essence of a god elevated to greatness through blood sacrifice.
Maguey root (agave tequilana or blue agave) is best known today as a component of tequila. Soaking the root in tequila or agave nectar makes for a wonderful offering, one that well mimics animal blood.
Maguey root can also be found (bottled in the way one can find ginseng root offered at Asian shops) at Spanish botanicas.
Note that this plant is also effective against malevolent witchcraft (sorcery).
Agave nectar is made in Mexico and South Africa, and (like tequila) it contains some maguey root (along with other species of agave). So you will need to purchase the root (as opposed to offering tequila or agave syrup alone).
When making your own blood offering (by pricking your finger) it would be auspicious to use a maguey thorn in doing so.
Give it a try (experiment with all of my suggestions), and let me know what kind of results you receive.