Abstract: A method of depopulating livestock is provided. The method comprises restricting the livestock in a defined space, and depositing foam into the defined space, forming a foam blanket covering the livestock. The livestock can be avians, such as chickens, ducks, and turkeys. A device for making medium expansion foam comprising a high expansion foam generator having a fan, and a shroud shielding the fan from ambient air intake. The shroud limits the amount of ambient air incorporated into the foam during operation. The device can include an alternative gas input positioned to direct an alternative gas to the fan. The alternative gas is selected from the group consisting of carbon dioxide, nitrogen, argon, and mixtures thereof.