Our number one parasite control is simply good managed rotational grazing. Done right his breaks the parasite life cycle.
Healthy animals help since parasites tend to go after already stressed animals.
As noted above, garlic is something we work. I've done double blind studies on it across multiple species with excellent results.
The pumpkin seeds are supported to work but even with the large number of pumpkins we grow I don't think we have enough for that and they're highly seasonal.
The cold of winter is another control.
In the end, if you have an animal that is struggling with worms I would suggest hitting it with Fenbendazole and Ivermec sequentially. Just observe the withdrawal times and double them if you want extra safety. I don't like the chemical dewormers because of concerns for the soil fauna but there are times for them. A fecal test is the best way to find out what is going on but observations of gums, inner eye lid, growth rate, coat and general condition all are indicators.
-Walter
See:
http://SugarMtnFarm.com/worms-au-natural