Chemicals in manure is a real issue, to be sure. Animal husbandry is still in the age of better living through chemicals, and worming is just one of many issues that are "solved using pesticides. I know my sourcing well; one of my guys is USDA registered organic and the other uses drugs in curative dosing, not preventative. I feel pretty comfortable about both.
Do your homework, though. At least ask the questions. Are these animals medicated? With what?
From [url=https://www.amazon.com/compost-tea-brewing-manual/dp/B0006S6JVK]Dr. Ingham's Compost Tea Manual[/url]... from the section on manure tea...
Antibiotics used in the animal feed are soluble and so normally extracted into the water and can cause significant trouble for microorganisms in the liquid extract.
But manure ain't compost, it's manure. Composting has been shown to [url=https://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/05/05/HOGD3PJOUT1.DTL]break down antiobiotics[/url], but pesticides are sterner stuff. Take B's aminopyralid (an herbicide often ingested by livestock). My understanding of chems is very weak but these [url=https://scienceblogs.com/moleculeoftheday/2008/06/aminopyralid_you_got_herbicide.php]geeks seem pretty freaked out[/url]by it's persistence in the environment. When science heads who do know chemistry say things Like "This is scary", then I'm scared too.
The most commonly used wormer, [url=https://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC42017]Ivermectin[/url] (used by humans, dogs, cats, livestock for worms, lice, scabies, and more) is an isolate from a naturally occuring soil bacteria, [url=https://www.ebi.ac.uk/2can/genomes/bacteria/Streptomyces_avermitilis.html]Streptomycetes avermitilis[/url], the source of many antibiotics, so likely that one is not a toxic issue for us, but there are indications that [url=https://www.springerlink.com/content/387363451x5k227w/]Ivermectin treated manures break down slower and have reduced biologies[/url]. Not what we have in mind when we compost... but organic...
You decide...
So ask...
HG