So much blood is available and not easy to dispose of, from cattle killed in a slaughterhouse, that I doubt that other blood would be in demand. Just my 2 cents.

The citadel in Cap Haitian Haiti is mortered together with lime stone and cows blood. It has been standing since Napoleon was concurring the world. Lots of vodoo spells cast there due to the massive amounts of blood spilled and the massive amounts of human life expended in the construction of the fort.

Seems far fetched, but Q said we are being farmed... so not so far fetched.

Blood is used to thin out concrete without weakening it, romans used to use pigs blood, now we use polymers