I have wormed my three year old flock twice. The first time was at almost two years old because I saw a worm in one of the roosters poops. I did it again several months later due to very wet weather and seeing them eat lots of worms from the ground. If you use Ivomec EPRINEX pour-on for cattle, you use a needleless syringe and squirt 1/2 cc behind the neck of the larger birds and 1/4 cc for bantams. Reapply in two weeks or so to get later-hatching worm eggs.
The rest of the time, I use natural wormers like buttermilk with chopped unsalted pumpkin seeds. It paralyzes the worms so they can be expelled in the poop. There is a follow-up with molasses in water to help the poop flow, so to speak and get those worms out. That's more of a preventative than a cure for a heavy load of worms, though. I dont plan to worm my birds unless I feel there is a specific reason. With Eprinex, there is no milk or meat withdrawal with cattle, so I continue eating eggs after using that. That would be up to you, though. Invermectin use would necessitate a withdrawal period, but it's only a guess for the actual time. I would do two weeks after the last meds are given, but that is really a guess.
