i have returned to chickens this year, and swatted up using a brilliant book by kate thear. which outlined all aspects. i have had some success and some failure. but i have reared lot's of chicks and have produced lot's of eggs, meat and spare poults for friends to start off with. worming has always been a grey area as you cannot guarantee that they will drink from the treated water source or eat the right amount of treated food. i use cider vinegar on a regular basis and also use grated carrot and garlic, but am never sure how much to give them. experts i have asked tell me just to go with the pharmacutical remedies, but i am concerned about withdrawl periods. unfortunately the previous occupants of our house had a flock of neglected birds, pigs and horses, so i am paranoid that the ground is infected with parasites, and i worry about not keeping up with treatment. the pigs don't mind my constant vigilence, some of the chickens have got used to being picked up and checked over , but the geese, forget it . w ith the hatching rates , don't be too worried, you can do everything within your capabillities and mother nature has the last word.