GARLIC GARLIC GARLIC grow your own, crush a couple of cloves or a bulb. put it into the drinking water. replenish once a week.
This worked for my flock for 20+ years. No doesn't make the eggs taste funny! Puts the lice off too. My dogs have garlic capsules, no worms or fleas !
I used to breed, always wormed pups at 3 weeks, never saw a worm because the mums were clear. The benefit of my ancient experience is, the less chemical interference, the better. If there's a problem with health, think what can you take away rather than what can you give. The exception to this rule is GARLIC and Homoeopathy! have fun, good luck