However, after the flood, when there was a population growth, the Hebrews were granted permission to eat meat. The Koran also prohibits ingestion of animal blood. The ability to store meat depends upon removing the blood from the flesh, and the most efficient way is to use the animal's heart. Thus, before slaughter, the animal is stunned, and bled before it dies. If not eaten fresh, it can be salted for preservation.
Slaughterhouses are bloody, and most folks consider blood distasteful.
The kosher slaughter is done swiftly to minimize animal trauma and allows the maximum amount of blood to be removed from the animal. What blood remains is soaked out in cold water. However, blood was consumed by other folks in medieval times. Marco Polo described the Mongol Army's method of feeding soldiers while on campaign. Each warrior on horseback had a string of 18 remounts.