I have never had a problem with Meyer. Did anybody else notice this person has only one post on here? The most common type of worms that chickens get do most of the damage in the first 2-3 weeks after they get them. If the birds had worms -deworm them. They dont die if you deworm them! Maybe you should not have waited until you lost 100 hens to check to see if they were sick. No laying is a pretty good sign.