As an organic livestock farmer (semi retired), currently studying soil biology, microbiomes, ecology and immunology I'd be happy to offer some views 'from the other end' as it were.

I can't think of many livestock production system where the excreta is added to water just for transport - on all organic farms, the productive re-use of the nutrients and organic matter - without endangering ecosystems or challenging flock/herd health with excessive exposure to pathogens and parasites - is a core system. The wastes are rarely 'sterile' from a pathogen or parasite point of view, but livestock with a robust constitution do not need to rely on anthelmintics or antibiotics to stay healthy, even with moderate levels of challenge. 'Clean' grazing would be allocated to the youngest stock, who have the least developed immunity.

I will follow with interest!

Susi