worms(bad ones)

Anyone have any methods of determining worms in chickens? Other than their feces.
A few red star hens seem on the smaller side and also decided to molt way to late and are now looking like dog food.
I will try to monitor feces but with deep litter and very cold temps I am having a hard time determining the presence of worms in the feces.
Interesting is that one red star same age as the others went broody this summer and avoided the incessant mounting by a rooster. She has not molted and I suspect will not molt until next fall. This rooster left three red stars with no feathers on their backs and these are the chickens that molted way too late.
One of these three has lost weight and seems a bit troubled.
One lesson learned is to have lots of hens for the rooster.

I just put bleach in there water once or twice a year, seems to keep them worm free. After they have drank the diluted bleach water I give them fermented foods or add a pro biotic to there water for month or so to rebuild the good flora ... works for me but im no expert.