This is a natural recipe that I have used for a while and it seems to do the trick. It calls for fresh turmeric which I have but when I didn't I used the powdered spice and I did not notice a difference.
This recipe uses a lot of chillies but don't be concerned for your chickens as they are not bothered but the heat of chillies. In fact they will strip a chillie bush bare given half the chance.
For 10 Chickens:
1 Litre of Full Cream Milk
6 Cloves of Garlic
1 TBS Paprika
1 TBS Fresh Turmeric or Ground (if you do not have access to fresh)
Crush the garlic and chop the Chillies then add both to the milk along with the diced fresh turmeric and paprika. Bring to a simmer the turn off the heat and leave over night.
The next morning reheat the mix to porridge temperature and if you have a stick blender use it to blend the mix. If not it will not matter as the chickens will still eat the chillies.
Mix your worming mix with 2 grated carrots and 1kg of layers mash.
Feed this first thing in the morning to chickens who have fasted for 24 hours, a week before the full moon. This is also a good time to dust your chickens for lice, we use Pestene.