Fodder means the animals that you kill to get a new butterfly for Sparx. So for this boss battle, you need to complete it witout killing any of the chickens to get a life back. The best way to get this trophy is to wait until you have gotten all the orbs and gems. This will give you an infinite fire ball. You can complete this boss fight in a couple of seconds with this powerup. You won't even need to worry about fodder during Gulps Overlook level since they will never even appear.