@4464071c Maybe it is so we can stop feeding cows blood & bird shit.

"Blood collected from a slaughterhouse was fermented with 10, 15 and 20% liquid molasses...indicating that fermentation was achieved... The preserved blood had a sweet smell..."  

Mmm, pairs well with some "Poultry litter <which had> an acceptable aroma"

"Processing of slaughterhouse blood and poultry litter and the effects on nutrient digestibility by steers"
https://www.sciencedirect.com/science/article/abs/pii/037784019390153B