The sacrificial beasts are allowed to live until the vow is fulfilled when they are slaughtered, a festive meal is eaten of the the meat, and the blood is poured on a witness pillar. When the vow is first made the animal is marked with some item of gold, usually a ring in either the ear or nose, or a collar in the case of birds.
The witness pillars are of unknown age and are found on the banks of the river in a couple locations. It is postulated that vows were originally tied to the river god but most information about the cult of the river has been lost. There is a clue to this tie in the name of the piscine predator sagar-jalaipon or the "oath-blood drinker-fish", a fish large enough to have been known to pull under deer who are drinking at the water's edge.