Go ahead and use valbazen even if it's roundworms. Valbazen kills all types of worms that chickens can get. 1/2cc for standards, 1/4cc for smaller birds. Redose in 10 days. Dont use zimectrin gold to go after roundworms. I use z-gold for stubborn cases of tapeworms.
The longest large roundworm I've seen is about 6 inches. I wouldnt eat the meat if they've been given a wormer. Worms are normally located in the digestive tract....I dont recommend eating their guts LOL.
If there's an infestation, worms can be excreted because one or two died or there's no more room in the digestive tract (see the photo above.)...then there's only one way to go...out the rear end. Natural products may help prevent, but are ineffective treating when there's an infestation. When you see worms in feces, it's usually an infestation and alot of damage has been done to the intestinal lining/wall in the digestive tract.
Your soil conditions dictate how often you should worm. Warm moist or wet soil may require frequent wormings. Dry desertlike or cold mountainous or rocky soils may require less.
