Minecraft wiki entry for Thunderstorm_survival, associated text: When killed, zombified piglins drop gold nuggets, rotten flesh and, occasionally, their own golden swords. However, they are difficult to kill and are neutral mobs only triggered by harm done by a player, unlike spiders and endermen. To replenish pigs, look for "wild" pigs, and bring them to your farm using a carrot, potato or beetroot. A separate pen or a roof can also be built to reduce the chances of losing every pig.