That is scary...I have looked on the internet at this Company and would not touch them with a bargepole...this may be an English expression but beware,,,there is no way I would entertain buying anything from this Company...thanks Cathy for bringing this to the attention of us all...!
If you have dry sandy soil...maybe once a year is OK...wet conditions you should worm every three to six months...depends on many factors as to when...
Signs of poop on their backsides
Less eggs than normal...except when moulting/Winter months
Loss of condition..., weight loss, pale...
As one expert in de-worming of chickens says...if their feet touch the ground they will get worms...
Depending upon soil conditions...chickens are normally treated every 3 - 6 months....
You hopefully will never see the worms...if you see them in the poop the chickens will be heavily...